Abstract
Stimulation of Dictyostelium cells with the chemoattractant cAMP results in transient phosphorylation of the myosin regulatory light chain (RLC). We show that myosin light chain kinase A (MLCK-A) is responsible for RLC phosphorylation during chemotaxis, and that MLCK-A itself is transiently phosphorylated on threonine-166, dramatically increasing its catalytic activity. MLCK-A activation during chemotaxis is highly responsive to cellular cGMP levels and the cGMP-binding protein GbpC. MLCK-A- cells have a partial cytokinesis defect, and do not phosphorylate RLC in response to concanavalin A (conA), but cells lacking cGMP or GbpC divide normally and phosphorylate in response to conA. Thus MLCK-A is activated by a cGMP/GbpC-independent mechanism activated during cytokinesis or by conA, and a cGMP/GbpC-dependent pathway during chemotaxis.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Carrier Proteins / chemistry
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Carrier Proteins / metabolism
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Chemotaxis
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Concanavalin A / pharmacology
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Cyclic GMP / metabolism*
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Cyclic GMP / pharmacology
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Cytokinesis
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Dictyostelium / cytology
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Dictyostelium / drug effects
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Dictyostelium / enzymology
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Enzyme Activation / drug effects
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Gene Deletion
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Intracellular Signaling Peptides and Proteins / chemistry
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Intracellular Signaling Peptides and Proteins / metabolism
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Models, Biological
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Myosin Light Chains / metabolism
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Myosin-Light-Chain Kinase / metabolism*
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Phosphorylation
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Signal Transduction / drug effects
Substances
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Carrier Proteins
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Intracellular Signaling Peptides and Proteins
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Myosin Light Chains
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cyclic GMP-binding protein
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Concanavalin A
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Myosin-Light-Chain Kinase
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Cyclic GMP