GTP binding protein 1 fragment [Multiple species], (C46H77N9O12), a peptide with the sequence H2N-Lys-Val-Ile-Thr-Phe-Ile-Asp-Leu-OH, MW= 948.16. G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins involved in transmitting chemical signals originating from outside a cell into the inside of the cell. G proteins function as molecular switches. Their activity is regulated by factors that control their ability to bind to and hydrolyze guanosine triphosphate (GTP) to guanosine diphosphate (GDP). When they bind GTP, they are 'on', and, when they bind GDP, they are 'off'. G proteins belong to the larger group of enzymes called GTPases(1). G proteins are important signal transducing molecules in cells. "Malfunction of GPCR [G Protein-Coupled Receptor] signaling pathways are involved in many diseases, such as diabetes, blindness, allergies, depression, cardiovascular defects, and certain forms of cancer. It is estimated that more than half of the modern drugs' cellular targets are GPCRs." (2)The human genome encodes roughly 950 G protein-coupled receptors, which detect photons (light), hormones, growth factors, drugs, and other endogenous ligands. Approximately 150 of the GPCRs found in the human genome have unknown functions.
Figure1 the structures of GTP binding protein
Figure 2 Mechanisms of GTP binding protein regulaltion
Ref:
1. Hurowitz EH, Melnyk JM, Chen YJ, Kouros-Mehr H, Simon MI, Shizuya H (2000). "Genomic characterization of the human heterotrimeric G protein alpha, beta, and gamma subunit genes". DNA Res 7 (2): 111–20.
2. Wu G (2010). "Assays with GPCRs". Assay Development: Fundamentals and Practices.New York: Wiley.