From the Burnham Institute, La Jolla, California 92037
Received for publication, October 7, 2002, and in revised form, November 4, 2002
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Seven in
absentia homologue (Siah) family proteins bind
ubiquitin-conjugating enzymes and target proteins for
proteasome-mediated degradation. Recently we identified a novel
Siah-interacting protein (SIP) that is a Sgt1-related molecule that
provides a physical link between Siah family proteins and the
Skp1-Cullin-F-box ubiquitin ligase component Skp1. In the
present study, a structure-based approach was used to identify
interacting residues in Siah that are required for association with
SIP. In Siah1 a large concave surface is formed across the dimer
interface. Analysis of the electrostatic surface potential of the Siah1
dimer reveals that the Siah1/Sina family
proteins represent mammalian homologs of the Drosophila Sina
(seven in absentia) protein. Sina
is required for R7 photoreceptor cell differentiation within the
sevenless pathway (1). The members of the family are E3
ubiquitin-protein isopeptide ligases that regulate ubiquitination and
protein degradation. For example, Sina binds a ubiquitin-conjugating
enzyme (E2). Heterocomplexes of Sina and another protein called
Phyllopod form an E3 complex that interacts with a transcriptional
repressor called Tramtrack, targeting it for polyubiquitination and
proteasome-mediated degradation (2, 3). The destruction of Tramtrack
is necessary for differentiation of R7 cells (2, 3).
In humans two genes exist that encode Sina-like proteins,
SIAH1 and SIAH2 (4). Like their
Drosophila counterpart, the Siah1 and Siah2 proteins contain
a N-terminal RING domain that binds E2s followed by a cysteine-rich
domain and then a novel domain implicated in binding various substrate
proteins and targeting them for degradation. The reported targets of
Siah-mediated degradation include DCC (5), Nco-R (6), c-Myb (7),
BOB1/OBF1 (8, 9), Peg3/Pw1 (10), APC (11), Kid (12), Numb (13),
synaptophysin (14), and group 1 metabotropic glutamate receptor (15).
In addition, Siah reportedly interacts with Vav, a GDP-exchange factor for Rac/Rho (16), and BAG1, a Hsp70/Hsc70-binding protein that modulates cellular pathways involved in control of cell proliferation, cell death, and cell migration (17). Interestingly, however, Siah does
not appear to target Vav or BAG1 for polyubiquitination and degradation
despite its ability to bind these proteins. Thus, not all Siah-binding
proteins are targets of Siah-mediated degradation. The physiological
basis for the broad range of protein-protein interactions with
Siah/Sina family members is as yet not clear.
Recently, we identified a novel Siah-interacting protein (SIP) by using
yeast two-hybrid interaction cloning methods (18). SIP is a
Sgt1-related protein that provides a physical link between Sina/Siah family proteins and the SCF complex component Skp1. Similar
to Siah/Sina family proteins, SCF complexes play a critical role
in the ubiquitination and degradation of a variety of target proteins
including cyclins, p27kip1, p21waf-1, E2F,
I The crystal structure of a fragment encompassing the Cys-rich domain
and the substrate-binding domain (SBD) of murine Siah1a has been
determined (22). The structure reveals that the SBD of Siah1a bears
striking structural similarity to the tumor necrosis factor
receptor-associated factor (TRAF) domains of TRAFs, a family of adapter
proteins that bridges the cytosolic domains of multiple tumor necrosis
factor family receptors to intracellular protein kinases (23). However,
the oligomeric state of Siah1a SBD differs from TRAFs. Siah1a exists as
a dimer, whereas TRAFs associate as trimers. In Siah1a a large concave
surface is formed across the dimer interface. This region as well as
two other clefts have been suggested as sites for protein-protein
interaction (22, 24). The results of the present study identify SIP
contact residues in the large concave surface of the Siah1 dimer, which
represent critical sites for the first docking event in the
Siah/SIP/Skp1/Ebi network.
Plasmids--
Mutations in Siah1 were generated by two-step
PCR-based mutagenesis using a full-length human Siah1 cDNA (17) as
a template. Products were purified by the QiaQuick gel extraction kit
(Qiagen), digested with EcoRI and XhoI, and then
directly subcloned into the EcoRI and XhoI sites
of pcDNA3 plasmid (Invitrogen) with a N-terminal Myc epitope-tag
(MEQKLISEEDL), thus creating pcDNA3-myc. Alternatively, the
cDNAs were subcloned into yeast two-hybrid plasmids pGilda
and pJG4-5, which produce fusion proteins with a LexA DNA-binding
domain or a B42 transcriptional activation domain, respectively,
at the N terminus under the control of a GAL1 promoter.
Transfections and Cell Culture--
HEK293T cells were
maintained in high glucose Dulbecco's modified Eagle's medium
containing 10% fetal calf serum, 1 mM
L-glutamine, and antibiotics. For transient transfections,
cells (~5 × 105) in 6-well plates were transfected
with plasmid DNAs using LipofectAMINE Plus (Invitrogen).
Immunoprecipitations--
HEK293T cells (2 × 106) in 100-mm plates were used directly or transiently
transfected with 6 µg (total) of plasmid DNA. After 24 h, cells
were treated with 10 µM MG132 for 8 h and lysed in 1 ml of HKMEN solution containing 10 mM HEPES (pH 7.2), 142 mM KCl, 5 mM MgCl2, 2 mM EGTA, 0.2% Nonidet P-40, 0.1 µM
phenylmethylsulfonyl fluoride, 5 µg/ml leupeptin, 1 µg/ml
aprotinin, 1 µg/ml pepstatin and 20 µM MG132.
Immunoprecipitations were performed using agarose-conjugated anti-Myc
antibody (9E10, Santa Cruz) at 4 °C for 4 h. After washing in
HKMEN solution, immune complexes were analyzed by
SDS-PAGE/immunoblotting using anti-hemagglutinin antibodies (3F10,
Invitrogen) followed by horseradish peroxidase-conjugated goat
anti-mouse or anti-rabbit immunoglobulin (Amersham Biosciences) and
detection using enhanced chemiluminescence (Amersham Biosciences).
Yeast Two-hybrid Assay--
For yeast two-hybrid assays (17),
the yeast EGY191 strain was cotransformed with pGilda plasmids encoding
wild-type or mutant Siah1/LexA DNA-binding domain fusion proteins,
pJG4-5 plasmids encoding SIP/B42 transactivation domain fusion
protein, and Reporter Gene Assays--
Tcf/LEF transcriptional activity was
measured by transient transfection reporter gene assays using reporter
plasmids pFOP-FLASH or pTOP-FLASH (containing wild-type or mutant
Tcf/LEF binding sites cloned upstream of a thymidine kinase minimal
promoter and luciferase gene, respectively) as described (25).
Structure of Siah1 Dimer--
The atomic model of Siah1a (22)
reveals three "clefts" or "grooves" located on the surface of
the Siah dimer that have potential as sites for protein-protein
interactions (24). The most striking is a large concave surface formed
at the dimer interface by an antiparallel arrangement of Interaction of Siah1 with SIP--
Because SIP is a basic protein,
we tested the role of the negatively charged residues in the concave
surface of the Siah1 dimer for binding of SIP, representing a cluster
of glutamic acids and aspartic acids in the concave
Two other regions were proposed as sites for protein-protein
interactions in Siah1a (22). These are electropositive clefts between
the SBD and two zinc fingers on each monomer (see Fig. 1). These
distinct sites are located at each end of the elongated dimer,
separated by 46 Å. The mutation of Arg-214, Arg-215, Arg-231, Arg-124,
and Arg-232 in these clefts to alanine did not block SIP binding (Fig.
2A).
Similar results with each of those mutant proteins were obtained using
yeast two-hybrid assays (Fig. 2B), confirming that the SIP
binding surface is located on one face of the Siah1 dimer in a concave
region (420 Å2) that contains a cluster of eight acidic
residues. In this predominately negatively charged area, two basic
residues (Arg-224 and Arg-233) are also found. To test the role of
these positively charged residues on SIP recognition, these two
arginines were mutated to alanine. The resulting mutant Siah1 molecule
retained the capability to bind SIP, suggesting that the
protein-protein interactions between Siah1 and SIP are mediated by
ionic contacts involving the negatively charged cluster.
Analysis of Function of Siah1 Mutant Proteins in Cells--
Siah
participates in a pathway leading to
To extend the present mutagenesis studies into a cellular context, we
took advantage of our previous findings showing that overexpression of
Siah1 induces degradation of
Because Separate and Distinct Protein-Protein Interaction Sites on
Siah1--
Siah1 also binds to the molecular co-chaperone BAG1, which
has been reported to abrogate growth arrest by Siah1 (17). Therefore, we tested the effects of mutations in the acidic clusters on Siah1 interaction with BAG1.
In contrast to SIP, BAG1 interacted with all of the mutant Siah1
proteins in the tested samples (Fig. 2), suggesting that SIP and
BAG1 bind to different surfaces of the Siah dimer. The Siah1-binding
domain of BAG1 is an
Recently, it was reported that the Drosophila protein
Phyllopod interacts with the SBD region of SINA, a close homologue of Siah1 (29). Deletion of five residues from the C terminus of the SBD
region of SINA completely abolished Phyllopod association, suggesting
that Phyllopod might interact with the concave cleft in the SINA dimer
because these residues are located in this large concavity (22).
Moreover, the authors showed by deletion analysis that a 19-amino acid
sequence in Phyllopod is necessary for binding to SINA (29). If this
segment in Phyllopod assumes ordered secondary structure, it could
easily be accommodated in a concave surface-like region in the Siah1
dimer that we have defined for SIP binding. Interestingly, there is no
apparent sequence similarity between SIP and the SINA-binding domain of
Phyllopod. The molecular basis for recognition of SIP and Phyllopod by
the Siah1/SINA homologues awaits future structural analyses of complexes.
The human SIP protein shares 93% identity at the protein level with a
mouse protein, previously identified as a calcyclin (S100A6)-binding
protein (CacyBP) (30). Interestingly, the CacyBP binds to S100 family
proteins through its C-terminal region in a
Ca2+-dependent fashion (31). Moreover, CacyBP
can be phosphorylated by protein kinase C in vitro (32). It
is still unclear whether Ca2+ or phosphorylation of
CacyBP/SIP affects its interactions with Siah1, Skp1, or other
proteins. Furthermore, the physiological effects of S100 family
proteins on Siah-induced degradation of
Because the large SIP-binding crevice identified here is formed by a
symmetrical arrangement of identical residues from the two Siah1
subunits, a question arises as to whether protein-protein interactions
with SIP involved the entire concave surface or intermolecular contacts
with just one monomer, that is, a half-site. We observed a similar
antiparallel arrangement of -sheet concavity is predominately
electronegative, suggesting that the protein-protein interactions
between Siah1 and SIP are mediated by ionic contacts. The structural
prediction was confirmed by site-directed mutagenesis of these
electronegative residues, resulting in loss of binding of Siah1 to SIP
in vitro and in cells. The results also provide a
structural basis for understanding the mechanism by which Siah family
proteins interact with partner proteins such as SIP.
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES
B, and
-catenin (19-21). We elucidated a network of protein interactions involving Siah and SIP that regulate levels of
-catenin and thus the activity of
-catenin-dependent
Tcf/LEF transcription factors. In this network an evolutionarily
conserved pattern exists where Siah binds to SIP, which interacts with
Skp1, which in turn binds to the F-box protein Ebi (18). Here, to begin
to dissect this network we have used site-directed mutagenesis to
identify the contact surfaces on Siah for SIP.
MATERIALS AND METHODS
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES
-galactosidase reporter plasmids (pRB1840).
-Catenin Measurements--
To detect exogenous cytosolic
-catenin, cells were disrupted in ice-cold hypotonic buffer
containing 10 mM Tris-HCl, pH 7.5, 10 mM KCl,
0.1 mM EDTA, and protease inhibitor mixture (Roche Molecular Biochemicals) by passage 15 times through a 26-gauge needle. Cell extracts were clarified by centrifugation at 16,000 × g for 30 min. Resulting supernatants (20 µg of total
protein) were separated by SDS-PAGE (10% gels) and transferred to
nitrocellulose membranes. Proteins were detected with anti-Myc
monoclonal antibody (9E10, Santa Cruz Biotechnology).
RESULTS AND DISCUSSION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS AND DISCUSSION
REFERENCES
-sheets
from each monomer (Fig. 1). The other two
are symmetrically equivalent clefts in each monomer that are located
between the Cys-rich domain that contains two zinc fingers and SBD. The
electrostatic surface potential of these regions is different (Fig. 1);
that is the central large
-sheet concavity is predominately
electronegative, whereas the two smaller clefts at the ends of the
oligomer are electropositive in nature. Thus, the potential exists for
binding at distant sites that differ significantly in overall
charge.
View larger version (54K):
[in a new window]
Fig. 1.
SIP binds to an electronegative concave
surface across the Siah1 dimer. Left panel, a ribbon diagram
is presented of the Siah1 dimer with the side chains for
negatively charged residues mutated in this study shown as ball
and stick models. Note that in this view the eight carboxylate
groups, contributed by residues Glu-161, Asp-162, Glu-226, and Glu-237
from each monomer, are located in a large concavity on one face of the
dimer. Right panel, the solvent-accessible surface of the
Siah1 dimer is shown colored according to electrostatic potential with
electronegative regions colored red and electropositive
surface features colored blue. This view is rotated 90°
relative to the left panel. Here the view is directly into
the concave surface, and residues that were mutated to alanine
resulting in a loss of SIP binding are labeled.
-sheet
structure. In contrast to wild-type Siah1 protein, mutant Siah1
molecules (mutant A) with alanine substituted for Glu-161, Asp-162,
Glu-226, and Glu-237 in the concavity failed to bind SIP in
co-immunoprecipitation experiments (Fig.
2A). Because Siah1 exists as a
dimer, the large electronegative surface concavity is formed by an
antiparallel orientation of identical
-sheets in each monomer. As
shown in Fig. 1, this arrangement produces a symmetrical relationship
between corresponding structural features of the monomeric subunits.
Consequently, eight acidic residues reside in the large concavity; that
is four from each monomer. Thus, substitution of alanine for four
acidic residues resulted in a loss of eight carboxyl groups at the
surface and a dramatic change in the electrostatic character of the
concavity. Failure of the mutant with these substitutions to bind SIP
identifies this concave region as the SIP-binding interface.
Substitution of alanine for Asp-253 and Glu-265 on the surface of the
opposite face of the dimer or Asp-142 and Gln-151 did not affect SIP
binding.
View larger version (50K):
[in a new window]
Fig. 2.
Generation of Siah1 mutants that fail to bind
SIP. A, HEK293T cells were transiently transfected with
plasmids encoding Myc-epitope tagged wild-type Siah1 (residues 91-282)
or various mutants as indicated and hemagglutinin-tagged SIP protein or
hemagglutinin-tagged BAG1 protein. The mutations were as follows:
A, E161A, D162A, E226A, E237A; B, N253A, Q265A;
C, R224A, R233A; D, R214A, R215A, R231A, R124A,
R232A; E, D142A, Q151A. Lysates were normalized for total
protein content and subjected to immunoprecipitation using
agarose-conjugated anti-Myc epitope monoclonal antibody (9E10). After
recovering immune complexes and washing, the immunoprecipitates were
analyzed by SDS-PAGE/immunoblotting using an anti-hemagglutinin
monoclonal antibody with ECL-based detection. As a control, 0.05 volume
of input cell lysate was loaded directly in the same gel. B,
yeast two-hybrid experiments were performed by transforming EGY191
(strain) cells. Wild-type Siah1 or various mutants, as indicated, were
expressed from the plasmid pGilda and tested for interactions with SIP,
which were expressed from the pJG4-5 plasmid. Interactions were
detected by transactivation of LEU2 reporter genes. Growth
on leucine-deficient medium at 30 °C was examined 4 days later.
Immunoblot analysis confirmed production of all LexA and B42 proteins
(not shown).
-catenin degradation involving
Siah and Ebi, an F-box protein that binds
-catenin independently of
the phosphorylation sites recognized by
-TrCP (18). We
identified a series of protein interactions that link Siah to
Ebi by association with SIP and Skp1, a central component of SCF.
Expression of Siah is induced by p53, suggesting a mechanism that links
genotoxic injury to destruction of
-catenin. In this process we
observed that reduced activity of
-catenin binding Tcf/LEF
transcription factors contributes to cell cycle arrest (18).
-catenin (18). We performed transient
transfection assays in HEK293T cells (Fig. 3A), monitoring
-catenin
protein levels by immunoblotting. As shown in Fig. 3A,
overexpression of wild-type Siah1 markedly reduced levels of
-catenin protein. In contrast, the Siah1 mutant with alanine
substitutions for the carboxylate cluster (mutant A) did not induce
degradation of
-catenin; rather, it enhanced levels of
-catenin.
Consistent with the binding results, the other mutant molecules
retained the ability to reduce levels of
-catenin.
View larger version (22K):
[in a new window]
Fig. 3.
Effect of wild-type and mutant Siah1 on
-catenin level and Tcf/LEF reporter activity.
A, HEK293T cells were transiently transfected with 0.2 µg
of plasmids encoding Myc-
-catenin with full-length wild-type Siah1
(0.5 µg) (wt), various mutant Siah1 (0.5 µg), or
fragment Siah1-(91-282)-(
R) as indicated (total DNA
amount normalized). After 24 h, cell lysates were prepared from
duplicated dishes of transfectants, normalized for total protein
content (20 µg per lane), and analyzed by SDS-PAGE/immunoblotting
using antibodies specific for Myc-
-catenin
(top) or Myc-Siah (bottom) with ECL-based
detection. B, HEK293T cells were transiently transfected
with a reporter gene plasmid (0.1 µg), which contains a Tcf/LEF
responsive element cloned upstream of a luciferase reporter gene
together with 0.01 µg of pCMV-
-gal as a transfection efficiency
control, and 0.1 µg of the indicated plasmids encoding
-catenin,
wild-type (WT), Siah1, or various mutants as indicated,
normalizing the total amount by the addition of empty pcDNA3 as
necessary. Luciferase activity was measured in cell lysates 24 h
later and normalized relative to
-galactosidase (mean ±S.D.,
n = 3).
-catenin is required as a cofactor for activation of the
transcription factor Tcf/LEF (26), we explored the effects of wild-type
and mutant Siah on Tcf/LEF activity using transient transfection
reporter gene assays (25, 27). Expression of
-catenin induced a
>10-fold increase in Tcf/LEF transcriptional activity in HEK293T (Fig.
3B). When an equivalent amount of plasmid DNA encoding Siah1
was co-transfected, Tcf/LEF activity was reduced by about half (Fig.
3B). In contrast to wild-type Siah1, transfecting cells with
plasmids encoding mutant A Siah1 failed to suppress
-catenin-mediated activation of Tcf/LEF and instead increased transactivation of the Tcf/LEF-responsive reporter gene plasmid, thus
confirming the specificity of the results. The other mutant Siah
molecules behaved as wild type in this assay. Thus, we concluded that
the contact residues required for interaction of Siah to SIP are
critical for the function of this protein in cells.
-helical bundle with an overall electronegative
charge (28). Interestingly, when basic residues at the two positively
charged crevices on Siah1 (Fig. 1) were mutated to alanine, binding to
BAG1 was retained. Thus the BAG1 binding site that is distinct from the
SIP interaction region has yet to be elucidated.
-catenin should be addressed.
-sheets in the dimeric MS2 translational
repressor (33, 34). In the repressor, residues that are required for
binding the RNA operator are located on six adjacent
-strands
contributed by residues in three strands from each monomer (35). As in
Siah1, a large concave crevice is formed across the dimer interface. In
the case of MS2, the dimeric repressor binds one RNA operator. One RNA
hairpin binds across the face of the dimer making asymmetric contacts
with residues from both monomers (36). For the Siah1 dimer it is
possible that the contact surface accommodates a single SIP molecule,
or alternatively, those two SIP molecules are bound to each symmetric half-site of the dimer. Further experiments are needed to determine the
binding stoichiometries of Siah-SIP interactions.
![]() |
ACKNOWLEDGEMENTS |
---|
We thank M. Cuddy and M. Fariborzi for technical assistance and R. Cornell for manuscript preparation.
![]() |
FOOTNOTES |
---|
* This work was supported by University of California Tobacco-Related Disease Research Program 9FT-0183.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
To whom correspondence should be addressed. Tel.: 858-646-3100 (Ext. 3509); Fax: 858-646-3194; E-mail: smatsuzawa@burnham.org.
Published, JBC Papers in Press, November 5, 2002, DOI 10.1074/jbc.M210263200
![]() |
ABBREVIATIONS |
---|
The abbreviations used are: Siah1, seven in absentia homologue 1; SIP, Siah-interacting protein; SBD, substrate-binding domain; HEK, human embryonic kidney; TRAF, tumor necrosis factor receptor-associated factor; SCF, Skp1-Cullin-F-box.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
1. | Carthew, R. W., and Rubin, G. M. (1990) Cell 63, 561-577[Medline] [Order article via Infotrieve] |
2. | Tang, A. H., Neufeld, T. P., Kwan, E., and Rubin, G. M. (1997) Cell 90, 459-467[Medline] [Order article via Infotrieve] |
3. | Li, S., Li, Y., Carthew, R. W., and Lai, Z.-C. (1997) Cell 90, 469-478[Medline] [Order article via Infotrieve] |
4. | Hu, G., Chung, Y. L., Glover, T., Valentine, V., Look, A. T., and Fearon, E. R. (1997) Genomics 46, 103-111[CrossRef][Medline] [Order article via Infotrieve] |
5. |
Hu, G.,
Zhang, S.,
Vidal, M.,
Baer, J. L.,
and Fearon, E. R.
(1997)
Genes Dev.
11,
2701-2714 |
6. |
Zhang, J.,
Guenther, M. G.,
Carthew, R. W.,
and Lazar, M. A.
(1998)
Genes Dev.
12,
1775-1780 |
7. |
Tanikawa, J.,
Ichikawa-Iwata, E.,
Kanei-Ishii, C.,
Nakai, A.,
Matsuzawa, S. I.,
Reed, J. C.,
and Ishii, S.
(2000)
J. Biol. Chem.
275,
15578-15585 |
8. |
Boehm, J., He, Y.,
Greiner, A.,
Staudt, L.,
and Wirth, T.
(2001)
EMBO J.
20,
4153-4162 |
9. |
Tiedt, R.,
Bartholdy, B. A.,
Matthias, G.,
Newell, J. W.,
and Matthias, P.
(2001)
EMBO J.
20,
4143-4152 |
10. |
Relaix, F.,
Wei, X.-J., Li, W.,
Pan, J.,
Lin, Y.,
Bowtell, D. D.,
Sassoon, D. A.,
and Wu, X.
(2000)
Proc. Natl. Acad. Sci. U. S. A.
97,
2105-2110 |
11. | Liu, J., Stevens, J., Hu, Y., Neufeld, K. L., White, R., and Matsunami, N. (2001) Mol. Cell 7, 927-936[CrossRef][Medline] [Order article via Infotrieve] |
12. | Germani, A., Bruzzoni-Giovanelli, H., Fellous, A., Gisselbrecht, S., Varin-Blank, N., and Calvo, F. (2000) Oncogene 19, 5997-6006[CrossRef][Medline] [Order article via Infotrieve] |
13. |
Susini, L.,
Passer, B. J.,
Amzallag-Elbaz, N.,
Juven-Gershon, T.,
Prieur, S.,
Privat, N.,
Tuynder, M.,
Gendron, M.-C.,
Israel, A.,
Amson, R.,
Oren, M.,
and Telerman, A.
(2001)
Proc. Natl. Acad. Sci. U. S. A.
98,
15067-15072 |
14. |
Wheeler, T. C.,
Chin, L. S., Li, Y.,
Roudabush, F. L.,
and Li, L.
(2002)
J. Biol. Chem.
277,
10273-10282 |
15. |
Ishikawa, K.,
Nash, S.,
Nishimune, A.,
Niki, A.,
Kaneko, S.,
and Nakanishi, S.
(1999)
Genes Cells
4,
381-390 |
16. |
Germani, A.,
Romero, F.,
Houlard, M.,
Camonis, J.,
Gisselbrecht, S.,
Fischer, S.,
and Varin-Blank, N.
(1999)
Mol. Cell. Biol.
19,
3798-3807 |
17. |
Matsuzawa, S.,
Takayama, S.,
Froesch, B. A.,
Zapata, J. M.,
and Reed, J. C.
(1998)
EMBO J.
17,
2736-2747 |
18. | Matsuzawa, S., and Reed, J. C. (2001) Mol. Cell 7, 915-926[CrossRef][Medline] [Order article via Infotrieve] |
19. | Koepp, D. M., Harper, J. W., and Elledge, S. J. (1999) Cell 97, 431-434[Medline] [Order article via Infotrieve] |
20. | Patton, E. E., Willems, A. R., and Tyers, M. (1998) Trends Genet. 14, 236-243[CrossRef][Medline] [Order article via Infotrieve] |
21. | Winston, J. T., Koepp, D. M., Zhu, C., Elledge, S. J., and Harper, J. W. (1999) Curr. Biol. 9, 1180-1182[CrossRef][Medline] [Order article via Infotrieve] |
22. | Polekhina, G., House, C. M., Traficante, N., Mackay, J. P., Relaix, F., Sassoon, D. A., Parker, M. W., and Bowtell, D. D. (2002) Nat. Struct. Biol. 9, 68-75[CrossRef][Medline] [Order article via Infotrieve] |
23. |
Arch, R. H.,
Gedrich, R. W.,
and Thompson, C. B.
(1998)
Genes Dev.
12,
2821-2830 |
24. | Reed, J. C., and Ely, K. (2002) Nat. Struct. Biol. 9, 8-10[CrossRef][Medline] [Order article via Infotrieve] |
25. |
Korinek, V.,
Barker, N.,
Morin, P. J.,
van Wichen, D.,
de Weger, R.,
Kinzler, K. W.,
Vogelstein, B.,
and Clevers, H.
(1997)
Science
275,
1784-1787 |
26. |
Peifer, M.,
and Polakis, P.
(2000)
Science
287,
1606-1609 |
27. |
Morin, P. J.,
Sparks, A. B.,
Korinek, V.,
Barker, N.,
Clevers, H.,
Vogelstein, B.,
and Kinzler, K. W.
(1997)
Science
275,
1787-1790 |
28. |
Briknarov![]() |
29. |
Li, S., Xu, C.,
and Carthew, R. W.
(2002)
Mol. Cell. Biol.
22,
6854-6865 |
30. | Filipek, A., and Kuznicki, J (1998) J. Neurochem. 70, 1793-1798[Medline] [Order article via Infotrieve] |
31. |
Filipek, A.,
Jastrzebska, B.,
Nowotny, M.,
Kwiatkowska, K.,
Hetman, M.,
Surmacz, L.,
Wyroba, E.,
and Kuznicki, J.
(2002)
J. Biol. Chem.
277,
21103-21109 |
32. |
Filipek, A.,
Jastrzebska, B.,
Nowotny, M.,
and Kuznicki, J.
(2002)
J. Biol. Chem.
277,
28848-28852 |
33. | Ni, C. Z., Syed, R., Kodandapani, R., Wickersham, J., Peabody, D. S., and Ely, K. R. (1995) Structure 3, 255-263[Medline] [Order article via Infotrieve] |
34. | Valegard, K., Liljas, L., Fridborg, K., and Unge, T. (1990) Nature 345, 36-41[CrossRef][Medline] [Order article via Infotrieve] |
35. | Lim, F., and Peabody, D. S. (1994) Nucleic Acids Res. 22, 3748-3752[Abstract] |
36. | Valegård, K., Murray, J. B., Stockley, P. G., Stonehouse, N. J., and Liljas, L. (1994) Nature 371, 623-626[CrossRef][Medline] [Order article via Infotrieve] |