P21(RAS) FARNESYLTRANSFERASE ALPHA-SUBUNIT AND BETA-SUBUNIT ARE PHOSPHORYLATED IN PC-12 CELLS - TGF-BETA SIGNALING PATHWAY INDEPENDENT PHOSPHORYLATION

Farnesyltransferase (FTase) catalyzes the transfer of a farnesyl isopr enoid to the conserved carboxyl-terminal cysteine residue of proteins terminating with the CAAX sequence. Rat brain FTase is a heterodimer c onsisting of a 49 kDa alpha-subunit and a 46 kDa beta-subunit. In this report, we show, for the first time, that the beta-subunit of FTase i s phosphorylated in vivo and the FTase heterodimer contains phosphoryl ated alpha/beta-subunits in rat adrenal medulla pheocytochroma PC-12 c ells. The presence of the phosphorylated FTase subunits as heterodimer in PC-12 cells which are known to be deficient in TGF-beta signaling pathways argues against the involvement of this pathway in their phosp horylation and heterodimerization. (C) 1997 Elsevier Science Ireland L td.