MARCKS, membranes, and calmodulin: kinetics of their interaction.
It is well documented that membrane binding of MARCKS (Myristoylated Alanine-Rich C-Kinase Substrate) requires both hydrophobic insertion of the N-terminal myristate into the bilayer and electrostatic interaction of the basic effector region with acidic lipids. The structure of a membrane-bound peptide corresponding to the effector region, residues 151-175 of bovine MARCKS, was recently determined using spin-labeled peptides and EPR. The kinetics of the peptide-membrane interaction were determined from stopped-flow fluorescence measurements; the adsorption of the peptide onto phospholipid vesicles is a diffusion-limited process. Five microM Ca2+-calmodulin decreases the lifetime of the peptide on a 100 nm diameter 10:1 PC/PS vesicle from 0.1 s to 0.01 s by rapidly pulling the peptide off the membrane. We propose a molecular mechanism, based on previous work by M. Eigen and colleagues, by which calmodulin may remove MARCKS(151-175) from the membrane at a diffusion-limited rate. Calmodulin may also use this mechanism to remove the pseudosubstrate region from the substrate binding site of enzymes such as calmodulin kinase II and myosin light chain kinase.
Arbuzova
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A
Department of Physiology and Biophysics, HSC, SUNY - State University of New York, Stony Brook, NY 11794-8661, USA.
Murray
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D
McLaughlin
S
S
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry*; D004058:Diffusion; D004789:Enzyme Activation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008051:Lipid Bilayers / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism
D002147:Calmodulin; D047908:Intracellular Signaling Peptides and Proteins; D008051:Lipid Bilayers; C000619710:MARCKS protein, human; D008565:Membrane Proteins; D011506:Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D009219:Myosin-Light-Chain Kinase