The stimulation of phosphorylation of intracellular proteins in GH3 rat pituitary tumour cells by phorbol esters of distinct biological activity.
Using a pituitary tumour cell line (GH3), we have studied the phosphorylation of intracellular proteins induced by phorbol esters of diverse biological activity. All the active phorbol esters, including the weakly tumour-promoting but non-platelet aggregatory compound DOPPA, stimulated the phosphorylation of a cytosolic 80 kDa protein. A protein of this molecular mass has been suggested to be a marker of PKC activity. In contrast, only TPA and the non-tumour promoting but highly active phorbol ester SAP A stimulated the phosphorylation of a 130 kDa membrane protein. The results suggest that these phorbol esters activate PKC, but induce the differential phosphorylation of a variety of intracellular proteins.
Brooks
S F
SF
Laboratory of Protein Structure, National Institute for Medical Research, Mill Hill, London.
Evans
F J
FJ
Aitken
A
A
D000818:Animals; D009363:Neoplasm Proteins / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010911:Pituitary Neoplasms / Q000473:pathology*; D051381:Rats; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism*
D009363:Neoplasm Proteins; D010703:Phorbol Esters; D010750:Phosphoproteins