Activation of wheat embryo calcium‐regulated protein kinase by unsaturated fatty acids in the presence and absence of calcium

Abstract

Unsaturated fatty acids (oleic, linoleic and arachidonic acids) markedly activate extensively purified wheat embryo Ca 2+ ‐regulated protein kinase in the absence of Ca 2+ or at very low free Ca 2+ levels (<0.4 μM). While oleic and linoleic acids also activate in the presence of Ca 2+ (10 −6 −10 −4 M), arachidonic acid inhibits at free Ca 2+ greater than 10 −5 M. Phosphatidylserine does not substantially activate in the absence of Ca 2+ or the presence of high Ca 2+ . Stearic and arachidic acids are less effective than the unsaturated fatty acids as activators in the absence of Ca 2+ . This type of plant protein kinase may be regulated in vivo independently of Ca 2+ through release of unsaturated fatty acids.