Anti-GGTI antibodies enable researchers to detect and measure the GGTI antigen in biological samples. This target is a reported synonym of the PGGT1B gene, which encodes protein geranylgeranyltransferase type I subunit beta. This protein is known to catalyze the transfer of a geranyl-geranyl moiety from geranyl-geranyl pyrophosphate to a cysteine at the fourth position from the C-terminus of proteins having the C-terminal sequence Cys-aliphatic-aliphatic-X. The human version of GGTI has a canonical amino acid length of 377 residues and a protein mass of 42.4 kilodaltons, although 2 isoforms have been identified. GGTI is a member of the Protein prenyltransferase subunit beta protein family.