Allosteric determinants in guanine nucleotide-binding proteins.
Proc Natl Acad Sci U S A
; 100(24): 14445-50, 2003 Nov 25.
Article
in En
| MEDLINE
| ID: mdl-14623969
ABSTRACT
Members of the G protein superfamily contain nucleotide-dependent switches that dictate the specificity of their interactions with binding partners. Using a sequence-based method termed statistical coupling analysis (SCA), we have attempted to identify the allosteric core of these proteins, the network of amino acid residues that couples the domains responsible for nucleotide binding and protein-protein interactions. One-third of the 38 residues identified by SCA were mutated in the G protein Gs alpha, and the interactions of guanosine 5'-3-O-(thio)triphosphate- and GDP-bound mutant proteins were tested with both adenylyl cyclase (preferential binding to GTP-Gs alpha) and the G protein beta gamma subunit complex (preferential binding to GDP-Gs alpha). A two-state allosteric model predicts that mutation of residues that control the equilibrium between GDP- and GTP-bound conformations of the protein will cause the ratio of affinities of these species for adenylyl cyclase and G beta gamma to vary in a reciprocal fashion. Observed results were consistent with this prediction. The network of residues identified by the SCA appears to comprise a core allosteric mechanism conferring nucleotide-dependent switching; the specific features of different G protein family members are built on this core.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
GTP-Binding Proteins
Type of study:
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
Proc Natl Acad Sci U S A
Year:
2003
Document type:
Article