BIOL 3156 Study Guide - Protein Kinase, Cytoplasm, Stat5
Document Summary
In signal transduction pathways there is always a cell surface receptor. Common theme: each spans the cell membrane as well as on the membrane, extracellular region, transmembrane region (simple and complex, cytoplasmic domain. Change transmitted through transmembrane portion and causes intracellular domain change. Activates some enzymatic activity (usually a kinase) phosphorylates lipids. Ligand causes a dimerization of two receptors with tyrosine-kinase residues at the cytoplasmic end. Tyrosine-kinase becomes phosphorylated and can interact with an adaptor protein in the cytoplasm. The adaptor proteins couples with gnrp (guanadine nucleotide releasing protein factor g protein). Gnrp causes phosphorylation of another g-protein called ras. When it is phosphorylated, it is activated and coupled to gtp. Ras-gtp complex acts as a kinase and phosphorylates raf. It is reversible to the inactive ras-gdp form is facilitated by a gtp unphosphorylase(gap). The transcriptoion factor is then phosphorylated and activated to start transcription.
