Protein kinase C during differentiation of human promyelocytic leukemia cell line, HL-60.

Protein kinase C (PKC) from human promyelocytic leukemia HL-60 cells can be resolved into three fractions (peak, a, b and c) by hydroxyapatite column chromatography. Peak a and c enzymes are indistinguishable from the brain type II PKC having beta (beta I and beta II)-sequence and type III having alpha-sequence, respectively. Peak b enzyme is a previously unidentified PKC subspecies that has enzymological properties subtly different from type I (having gamma-sequence), type II and type III PKC. Upon treatment of HL-60 cells with 1 microM retinoic acid, this peak b enzyme is decreased dramatically within 24 h, whilst peak a enzyme (beta-PKC) is increased, and peak c (alpha-PKC) enzyme is slightly decreased within 48 h. The result implies that the PKC subspecies in HL-60 cells have distinct functions during cell differentiation.