Protein kinase C isoforms in murine erythroleukemia cells and their involvement in the differentiation process

Abstract
In addition to α, δ and ε‐protein kinase C, murine erythroleukemia cells contain ζ‐PKC and also a c‐PKC isoform, named α1, which shows cross‐reactivity with an anti‐α‐PKC antipeptide antibody. In a C44 MEL cell clone, characterized by a high rate of differentiation, both c‐PKC forms are expressed at a level higher than that of the N23 MEL cell clone which differentiates at a low rate and contains higher levels of ε‐PKC and particularly of the δ‐PKC isozyme. In the course of MEL cell differentiation, δ‐PKC in N23 cells and α1‐PKC in C44 cells are rapidly down‐regulated and the overall process is almost completed before cell commitment. Of the other three PKC isozymes present in both clones, only α‐PKC is down‐regulated to a significant extent. It is proposed that modulation of the signal delivered by each PKC isozyme is one of the biochemical mechanisms involved in MEL cell differentiation.