Author(s): Ho C, Slater SJ, Stagliano B, Stubbs CD
Abstract Share this page
Abstract The activity of membrane-associated protein kinase C (PKC) is tightly controlled by the physical properties of the membrane lipid bilayer, in particular, curvature stress, which is induced by bilayer-destabilizing lipid components. An important example of this is the weakened lipid headgroup interactions induced by phosphatidylethanolamine (PE) and cholesterol. In this work our previous observation with a mixed isoform PKC showing a biphasic dependence of activity as a function of membrane curvature stress [Slater et al. (1994) J. Biol. Chem. 269, 4866-4871] was here extended to individual isoforms. The Ca(2+)-dependent PKCalpha, PKCbeta, and PKCgamma, along with Ca(2+)-independent PKCdelta, but not PKCepsilon or PKCzeta, displayed a biphasic activity as a function of membrane PE content. The fluorescence anisotropy of N-(5-dimethylaminonaphthalene-1-sulfonyl)dioleoylphosphatidylserine (dansyl-PS), which probes the lipid environment of PKC, also followed a biphasic profile as a function of PE content for full-length PKCalpha, PKCbetaIotaIota, and PKCgamma as did the isolated C1 domain of PKCalpha. In addition, the rotational correlation time of both PKCalpha and PKCdelta C1-domain-associated sapintoxin D, a fluorescent phorbol ester, was also a biphasic function of membrane lipid PE content. These results indicate that the C1 domain acts as a sensor of the bilayer surface properties and that its conformational response to these effects may directly underlie the resultant effects on enzyme activity.
This article was published in Biochemistry
and referenced in Journal of Clinical & Cellular Immunology