Structure of small G proteins and their regulators.
In recent years small G proteins have become an intensively studied group of regulatory GTP hydrolases involved in cell signaling. More than 100 small G proteins have been identified in eucaryotes from protozoan to human. The small G protein superfamily includes Ras, Rho Rab, Rac, Sarl/Arf and Ran homologs, which take part in numerous and diverse cellular processes, such as gene expression, cytoskeleton reorganization, microtubule organization, and vesicular and nuclear transport. These proteins share a common structural core, described as the G domain, and significant sequence similarity. In this paper we review the available data on G domain structure, together with a detailed analysis of the mechanism of action. We also present small G protein regulators: GTPase activating proteins that bind to a catalytic G domain and increase its low intrinsic hydrolase activity, GTPase dissociation inhibitors that stabilize the GDP-bound, inactive state of G proteins, and guanine nucleotide exchange factors that accelerate nucleotide exchange in response to cellular signals. Additionally, in this paper we describe some aspects of small G protein interactions with down-stream effectors.
Paduch
M
M
Institute of Biochemistry and Molecular Biology, University of Wrocław, Poland.
Jeleń
F
F
Otlewski
J
J
D000595:Amino Acid Sequence; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins