MCDB 418 Lecture Notes - Lecture 15: Protein Phosphatase 2, Complex Differential Form, Structural Motif
2 Apr 2017
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Lecture 15: calcium as a 2nd messenger and the ca/calmodulin signaling pathway. 1953, hokin & hokin - ach stimulated phosphoinositide (pi) turnover (pi effect) Hormones that stimulate pi breakdown also stimulate ca influx. Ca ionophores mimicked hormonal effect without affecting pi breakdown (not true in all systems) Hormones pi breakdown cytoplasmic ca level increase. Binding of hormone to receptor tyrosine kinase (rtk) or g protein coupled receptor (gpcr) activates membrane bound enzymes, phospholipase (plc) Rtks phosphorylate + activate plc (pdgf-r plc) Gpcrs use gq proteins to activate plc . Plcs hydrolyze phosphatidylinositol-4,5-p2 (pip2) to inositol triphosphate (ip3) + diacylglycerol (dag) Ip3 mobilizes ca from intracellular sources (smooth endoplasmic reticulum and mitochondria) Why ca: ability of cells to change the intracellular free ca over a wide range. Tremendous concentration gradient between extracellular and intracellular ca concentrations. 1 (2) mm (outside) vs. 0. 01 um to 10 um (inside) Large gradient maintained by a group of ca transport atpase (pumps) (ca/mg atpase,
