RT Journal Article SR Electronic T1 SH2 and PTB Domains in Tyrosine Kinase Signaling JF Science's STKE JO Sci. STKE FD American Association for the Advancement of Science SP re12 OP re12 DO 10.1126/stke.2003.191.re12 VO 2003 IS 191 A1 Schlessinger, Joseph A1 Lemmon, Mark A. YR 2003 UL http://stke.sciencemag.org/content/2003/191/re12.abstract AB Intracellular signaling pathways that involve protein tyrosine kinases (PTKs) are critical for the control of most cellular processes. Dysfunctions in PTKs, or in the signaling pathways that they regulate, result in a variety of diseases such as cancer, diabetes, immune deficiency, and many others. SH2 (Src homology region 2) and PTB (phosphotyrosine-binding) domains are small protein modules that mediate protein-protein interactions involved in many signal transduction pathways. Both domains were initially identified as modules that recognize phosphorylated tyrosines in receptor tyrosine kinases and other signaling proteins. Subsequent studies have shown that, while binding of SH2 domains to their target proteins is strictly regulated by tyrosine phosphorylation, most PTB domains actually bind to their (nonphosphorylated) targets constitutively. The functions of SH2 and PTB domains include targeting of their host proteins to different cellular compartments, assembly of key components of signaling pathways in response to extracellular signals, and the control of autoinhibition, activation and dimerization of their host proteins. The information flow from the cell surface to different cellular compartments to regulate the cell cycle, cell shape and movement, cell proliferation, differentiation and cell survival are all controlled in part by SH2 and PTB domains that can recognize phosphotyrosine or particular amino acid sequence motifs in a wide variety of target molecules.