RAB Geranylgeranyltransferase Alpha Subunit (RABGGTa)

RABGGTa encodes a 567-amino acid polypeptide. Homology to the transglutaminase gene, TGM1, which maps to 14q11, indicated that this subunit was located on the same chromosomal band; Southern blot analysis confirmed this locus. Further analysis revealed that the RABGGTA and TGM1 genes are located only 2 kb apart in head-to-tail tandem arrangement; however, these 2 genes are not likely to be functionally related.

The third identified prenyltransferase is a GGTase that recognizes proteins that terminate in the sequence cys-X-cys or cys-cys. Its substrates include a large family of related membrane-associated GTP-binding proteins termed RAB proteins. RAB GGTase is composed of 2 tightly associated subunits, alpha (RABGGTA) and beta (RABGGTB).