Identification of a novel protein kinase C inhibitor in microsomes from phytohaemagglutinin activated human peripheral blood mononuclear cells.
A peptide inhibiting either corpuscolate or purified PKC has been identified from microsomes of PHA-activated human PBMC but it is not detectable in microsomes of resting PBMC. The peptide was obtained from a microsomal preparation in an oligomeric form that could be transformed into a monomeric form by beta-MSH. The active peptide (IN) was retained on a PC-11 chromatographic column and could be eluted with NaCl. IN is ineffective on PKC-dependent protamine phosphorylation of protamine and on Ca2+ and phospholipid-independent activity generated by mild hydrolysis with trypsin of PKC. Ca2+ binding is permissive for IN activity. IN inhibits particulate PKC in PHA-activated PBMC, but is ineffective after TPA activation. All these data indicate that IN acts at the regulatory domain of PKC.
Gandini
E
E
Institute of Medical Genetics, University of Ferrara, Italy.
Orlando
P
P
Selvatici
R
R
Balboni
A
A
Boninsegna
S
S
Rubini
M
M
D001798:Blood Proteins / Q000032:analysis* / Q000502:physiology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000032:analysis; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000737:chemistry* / Q000187:drug effects / Q000276:immunology; D008861:Microsomes / Q000737:chemistry*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D001798:Blood Proteins; D004791:Enzyme Inhibitors; D010835:Phytohemagglutinins; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate