Publication Date:
1995-11-10
Description:
Crystallographic analysis of 2.2 angstrom resolution shows that guanosine triphosphate (GTP) hydrolysis triggers conformational changes in the heterotrimeric G-protein alpha subunit, Gi alpha 1. The switch II and switch III segments become disordered, and linker II connecting the Ras and alpha helical domains moves, thus altering the structures of potential effector and beta gamma binding regions. Contacts between the alpha-helical and Ras domains are weakened, possibly facilitating the release of guanosine diphosphate (GDP). The amino and carboxyl termini, which contain receptor and beta gamma binding determinants, are disordered in the complex with GTP, but are organized into a compact microdomain on GDP hydrolysis. The amino terminus also forms extensive quaternary contacts with neighboring alpha subunits in the lattice, suggesting that multimers of alpha subunits or heterotrimers may play a role in signal transduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mixon, M B -- Lee, E -- Coleman, D E -- Berghuis, A M -- Gilman, A G -- Sprang, S R -- DK 46371/DK/NIDDK NIH HHS/ -- GM34497/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1995 Nov 10;270(5238):954-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9050, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7481799" target="_blank"〉PubMed〈/a〉
Keywords:
Binding Sites
;
Crystallography, X-Ray
;
GTP-Binding Proteins/*chemistry/metabolism
;
Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
;
Guanosine Diphosphate/*metabolism
;
Guanosine Triphosphate/*metabolism
;
Hydrogen Bonding
;
Hydrolysis
;
Magnesium/metabolism
;
Models, Molecular
;
*Protein Conformation
;
Protein Structure, Secondary
;
*Protein Structure, Tertiary
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
