Role of Vav1, a hematopoietic signal transduction molecule, as an adaptor protein in health and disease

Abstract

The growth and differentiation of normal cells are controlled by protein-tyrosine kinases, which serve as receptors for a wide variety of external signals. Small protein modules called Src homology 2 (SH2) and SH3 domains mediate protein-protein interactions in signaling pathways that are triggered by protein tyrosine kinases. The SH2 domain, a protein module of around 100 amino acids, is present in tyrosine kinase targets within the cell. SH2 domains are recruited to activated and autophosphorylated growth factor receptors by directly recognizing tyrosine phosphorylation sites. Growth factor receptors and other phosphoproteins have short phosphotyrosine (pTyr)-containing sequences that are bound by SH2 domains. The SH3 domain, a distinct element of approximately 50 residues that recognizes proline-rich and hydrophobic-amino-acid-containing regions, is frequently found in SH2-containing proteins. Tyrosine kinases can be coupled to downstream targets with SH3-binding sites by proteins with SH2 and SH3 domains acting as adaptors. These intricate and precise biochemical signaling pathways result in the regulation of gene expression, cytoskeletal architecture, and cell metabolism. The role of SH2/SH3 proteins in T cell signaling will be discussed. A special focus will be on the role of the hematopoietic signal transducer with SH2/SH3 domains, Vav1, in health and cancer.