Cloning and expression of a cDNA encoding the alpha subunit of rat p21ras protein farnesyltransferase (original) (raw)

The complete amino acid sequence of the a subunit of heterodimeric p2l' protein farnesyltransferase from rat has been deduced from the sequence of a cloned cDNA. The cDNA encodes a 377-amino acid protein that migrates on NaDodSO4/polyacrylamide gels identically to the a subunit purified from rat brain. When introduced into mammalian cells by tansfection, the cDNA for the a subunit produced no immunodetectable protein or farnesyltranderase activity unless the cells were simultaneously transfected with a cDNA encoding j3 subunit. In light of previous evidence that a subunit forms a heterodimer with at least two different 13 subunits, current data suggest a mechanism for coordinating amounts of a and 13 subunits. If an a subunit were stable only as a complex with a P subunit, the number of a subunits would be automatically maintained at a level just sufficient to balance all 13 subunits, thereby avoiding the potentially toxic overaccumulation of free a subunits.