Increased degradation of protein kinase C without diminution of mRNA level after treatment of WEHI-231 B lymphoma cells with phorbol esters.

Immunoblot analysis of WEHI-231 B lymphoma cell homogenates revealed that both type II, a major component, and type III, a minor component, protein kinase C (PKC) were present. Northern blot analysis of PKC mRNA showed a higher level of beta II and beta I mRNA (encoding type II PKC) than of alpha mRNA (encoding type III PKC). Short term (3 min) treatment with phorbol 12-myristate 13-acetate (PMA) caused a rapid loss of PKC in cytosol and a concomitant increase in the particulate fraction. After prolonged (24 hr) exposure, the level of both PKC isozymes were decreased. However, the corresponding mRNA levels remained intact. PMA did not inhibit the anti-IgM-mediated increase in [Ca2+]i in PKC-depleted cells.