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: 1) stimulant/ Ca²⁺/phospholipid-dependent C-kinase, eluted from DEAE 52 cellulose at 0.08-0.16 M NaCl; 2) stimulant/Ca²⁺/phospholipid-independent protein kinase M (M-kinase), and 3) 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.