Protein Geranylgeranyltransferase Type I Beta (PGGT1b)

Protein geranylgeranyltransferase type I (GGTase-I) transfers a geranylgeranyl group to the cysteine residue of candidate proteins containing a C-terminal CAAX motif in which 'A' is an aliphatic amino acid and 'X' is leucine . The enzyme is composed of a 48-kD alpha subunit (FNTA) and a 43-kD beta subunit, encoded by the PGGT1B gene. The FNTA gene encodes the alpha subunit for both GGTase-I and the related enzyme farnesyltransferase.

The sequences from both species encode a 377-amino acid polypeptide with a predicted molecular mass of 42.4 kD (human) and 42.5 kD (rat). Amino acid sequence comparisons suggested that the mammalian beta-subunit protein is the counterpart of the Saccharomyces cerevisiae gene CDC43.