Characterization of Ca2+-activated, phospholipid-dependent protein kinase C/protein kinase M in guinea pig peritoneal exudate macrophages.

Protein kinase C (C-kinase) is shown to be present in the cytosolic and particulate fractions of mineral oil induced peritoneal macrophages of guinea pigs. By omission or use of a high concentration of leupeptin, three forms of the enzyme were obtained: stimulant/Ca2+/phospholipid-dependent C-kinase, eluted from DEAE 52 cellulose at 0.08-0.16 M NaCl; stimulant/Ca2+/phospholipid-independent protein kinase M (M-kinase), and Ca2+-inhibited & stimulant/phospholipid-dependent form of protein kinase, both eluted from DEAE 52 cellulose at 0.18-0.22 M NaCl. Phorbol ester or 1,2-diacylglycerol were used as stimulants. It is suggested that Ca2+-inhibited & stimulant/phospholipid-dependent protein kinase represents the in vivo form of the M-kinase in intact cells.