Arachidonate and other unsaturated long-chain fatty acids were found to activate protein kinase C from human neutrophils. Kinase activation by arachidonate required calcium and was enhanced by diolein but did not require exogenous phosphatidylserine. Submaximal levels of arachidonate also enhanced the affinity of the kinase for calcium during activation by phosphatidylserine. Thus the release of arachidonate, which is triggered in many cell types by ligand-receptor interactions, could play a second messenger role in the regulation of cellular function by activation of protein kinase C.

http://science.sciencemag.org/content/sci/224/4649/622.full.pdf

A potential second messenger role for unsaturated fatty acids: activation of Ca2+-dependent protein kinase.

https://febs.onlinelibrary.wiley.com/doi/epdf/10.1016/0014-5793%2878%2980772-8

Identification of the Ca2+-dependent modulator protein as the fourth subunit of rabbit skeletal muscle phosphorylase kinase.

Phosphorylation of smooth muscle myosin light chain kinase by the catalytic subunit of adenosine 3': 5'-monophosphate-dependent protein kinase.

A role of calcium-activated phospholipid-dependent protein kinase in human platelet activation. Comparison of thrombin and collagen actions.

(1982). Regulatory Mechanisms in the Control of Protein Kinase. Critical Reviews in Biochemistry: Vol. 12, No. 2, pp. 133-186.

Regulatory mechanisms in the control of protein kinases.

1. A procedure is described for the isolation of myosin light-chain kinase from rabbit fast skeletal muscle as a homogeneous protein. 2. Myosin light-chain kinase is a monomeric enzyme of mol.wt. 77000. Under some conditions of storage it is converted into components of mol.wts. about 50000 and 30000 that possess enzymic activity. 3. The enzyme is clearly different in structure and properties from any other protein kinase so far isolated from muscle. 4. The enzyme is highly specific for the P-light chain (18000-20000-dalton light chain) of myosin and requires Ca2+ for activity. 5. The P-light chain is phosphorylated at a similar rate whether isolated or associated with the rest of the myosin molecule. 6. The effects of pH, bivalent cation and other nucleotides on the enzymic activity are described. 7. The role of the phosphorylation of the P-light chain of myosin in muscle function is discussed.

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S V Perry

Papers

Purification and properties of myosin light-chain kinase from fast skeletal muscle.