BIOLOGY 2B03 Lecture Notes - Lecture 14: Guanine, Grb2, Gtpase
Document Summary
Progenitor stem cells receive a signal to stop dividing but to differentiate into erythrocytes (rbcs). The signal is erythropoietin (epo): a cytokine which induces differentiation into rbcs. Epo expression is regulated by an oxygen-binding transcription factor in kidney cells. When epo is released into the circulatory system, only progenitor cells with an epo receptor (epor) (a cytokine receptor linked to the jak-stat signal transduction pathway) will bind to epo. Epor is inactive as a monomeric, single pass transmembrane protein but when epo binds with 2 epo receptors, they dimerize and become active. Has 3 functional domains: cytosolic domain, transmembrane domain, extracellular domain. Jak kinase: a protein that can autophosphorylate other jak kinases. And can phosphorylate the tyrosine (t) residues on targets. Kinase is inactive and kinases activity is weak, but dimerization from epo causes the jak kinases to come close together and can autophosphorylate each other to activate kinase activity.
