1i4t: Difference between revisions
New page: left|200px<br /> <applet load="1i4t" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i4t, resolution 2.6Å" /> '''CRYSTAL STRUCTURE AN... |
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[[Image:1i4t.gif|left|200px]]<br /> | [[Image:1i4t.gif|left|200px]]<br /><applet load="1i4t" size="350" color="white" frame="true" align="right" spinBox="true" | ||
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caption="1i4t, resolution 2.6Å" /> | caption="1i4t, resolution 2.6Å" /> | ||
'''CRYSTAL STRUCTURE ANALYSIS OF RAC1-GMPPNP IN COMPLEX WITH ARFAPTIN'''<br /> | '''CRYSTAL STRUCTURE ANALYSIS OF RAC1-GMPPNP IN COMPLEX WITH ARFAPTIN'''<br /> | ||
==Overview== | ==Overview== | ||
Small G proteins are GTP-dependent molecular switches that regulate | Small G proteins are GTP-dependent molecular switches that regulate numerous cellular functions. They can be classified into homologous subfamilies that are broadly associated with specific biological processes. Cross-talk between small G-protein families has an important role in signalling, but the mechanism by which it occurs is poorly understood. The coordinated action of Arf and Rho family GTPases is required to regulate many cellular processes including lipid signalling, cell motility and Golgi function. Arfaptin is a ubiquitously expressed protein implicated in mediating cross-talk between Rac (a member of the Rho family) and Arf small GTPases. Here we show that Arfaptin binds specifically to GTP-bound Arf1 and Arf6, but binds to Rac.GTP and Rac.GDP with similar affinities. The X-ray structure of Arfaptin reveals an elongated, crescent-shaped dimer of three-helix coiled-coils. Structures of Arfaptin with Rac bound to either GDP or the slowly hydrolysable analogue GMPPNP show that the switch regions adopt similar conformations in both complexes. Our data highlight fundamental differences between the molecular mechanisms of Rho and Ras family signalling, and suggest a model of Arfaptin-mediated synergy between the Arf and Rho family signalling pathways. | ||
==About this Structure== | ==About this Structure== | ||
1I4T is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with MG and GNP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1I4T is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=GNP:'>GNP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I4T OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Gamblin, S | [[Category: Gamblin, S J.]] | ||
[[Category: Justin, N.]] | [[Category: Justin, N.]] | ||
[[Category: Smerdon, S | [[Category: Smerdon, S J.]] | ||
[[Category: Tarricone, C.]] | [[Category: Tarricone, C.]] | ||
[[Category: Xiao, B.]] | [[Category: Xiao, B.]] | ||
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[[Category: signaling protein]] | [[Category: signaling protein]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:07:58 2008'' | ||
Revision as of 14:08, 21 February 2008
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CRYSTAL STRUCTURE ANALYSIS OF RAC1-GMPPNP IN COMPLEX WITH ARFAPTIN
OverviewOverview
Small G proteins are GTP-dependent molecular switches that regulate numerous cellular functions. They can be classified into homologous subfamilies that are broadly associated with specific biological processes. Cross-talk between small G-protein families has an important role in signalling, but the mechanism by which it occurs is poorly understood. The coordinated action of Arf and Rho family GTPases is required to regulate many cellular processes including lipid signalling, cell motility and Golgi function. Arfaptin is a ubiquitously expressed protein implicated in mediating cross-talk between Rac (a member of the Rho family) and Arf small GTPases. Here we show that Arfaptin binds specifically to GTP-bound Arf1 and Arf6, but binds to Rac.GTP and Rac.GDP with similar affinities. The X-ray structure of Arfaptin reveals an elongated, crescent-shaped dimer of three-helix coiled-coils. Structures of Arfaptin with Rac bound to either GDP or the slowly hydrolysable analogue GMPPNP show that the switch regions adopt similar conformations in both complexes. Our data highlight fundamental differences between the molecular mechanisms of Rho and Ras family signalling, and suggest a model of Arfaptin-mediated synergy between the Arf and Rho family signalling pathways.
About this StructureAbout this Structure
1I4T is a Protein complex structure of sequences from Homo sapiens with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
The structural basis of Arfaptin-mediated cross-talk between Rac and Arf signalling pathways., Tarricone C, Xiao B, Justin N, Walker PA, Rittinger K, Gamblin SJ, Smerdon SJ, Nature. 2001 May 10;411(6834):215-9. PMID:11346801
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