Characterization of a protein kinase-phosphoprotein system in free cytoplasmic ribonucleoprotein particles of plasma cell tumours.

A protein kinase, associated with free cytoplasmic ribonucleoprotein particles (free dRNP) has been purified from mouse plasma cell tumours. This protein kinase is able to phosphorylate in vitro endogenous protein from free dRNP. Some characteristics of this protein kinase have been studied. This protein kinase behaves as being cyclic AMP independent. The properties of this protein kinase were compared with other protein kinases: soluble, ribosome-bound, and nuclear protein kinases. Although there are minor differences it is very similar to a ribosome-associated protein kinase from the plasma cell tumours.