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Geranylgeranyltransferase type 1 or simply geranylgeranyltransferase is one of the three enzymes in the prenyltransferase group. In specific terms, Geranylgeranyltransferase (GGTase 1) adds a 20-carbon isoprenoid called a geranylgeranyl group to proteins bearing a CaaX motif: a four-amino acid sequence at the carboxyl terminal of a protein. Geranylgeranyltransferase inhibitors are being investigated as anti-cancer agents.

Function

Prenyltransferases, including geranylgeranyltransferase, posttranslationally modify proteins by adding an isoprenoid lipid called a prenyl group to the carboxyl terminus of the target protein. This process, called prenylation, causes prenylated proteins to become membrane-associated due to the hydrophobic nature of the prenyl group. Most prenylated proteins are involved in cellular signaling, wherein membrane association is critical for function.

Structure

Geranylgeranyltransferase contains two subunits, α and β that are encoded by the FNTA and PGGT1B genes, respectively. Both subunits are composed primarily of alpha helices. Geranylgeranyltransferase coordinates a zinc cation on its β subunit at the lip of the active site. Geranylgeranyltransferase has a hydrophobic binding pocket for geranylgeranyl diphosphate, the lipid donor molecule. All Geranylgeranyltransferase substrates invariably have a cysteine as their fourth-to-last residue. This cysteine, coordinated by the zinc, engages in an SN2 type attack on the geranylgeranyl diphosphate, displacing the diphosphate.

See also

• Farnesyltransferase
• Prenylation
• Rab geranylgeranyltransferase – Geranylgeranyltransferase type 2

References

1. ^ Lane KT, Beese LS (April 2006). "Thematic review series: lipid posttranslational modifications. Structural biology of protein farnesyltransferase and geranylgeranyltransferase type I". J. Lipid Res. 47 (4): 681–99. doi:10.1194/jlr.R600002-JLR200. PMID 16477080.
2. Reid TS, Terry KL, Casey PJ, Beese LS (October 2004). "Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity". J. Mol. Biol. 343 (2): 417–33. doi:10.1016/j.jmb.2004.08.056. PMID 15451670.
3. Long SB, Casey PJ, Beese LS (October 2002). "Reaction path of protein farnesyltransferase at atomic resolution". Nature. 419 (6907): 645–50. Bibcode:2002Natur.419..645L. doi:10.1038/nature00986. PMID 12374986. S2CID 4412580.

Further reading

• Eastman RT, Buckner FS, Yokoyama K, Gelb MH, Van Voorhis WC (February 2006). "Thematic review series: lipid posttranslational modifications. Fighting parasitic disease by blocking protein farnesylation". J. Lipid Res. 47 (2): 233–40. doi:10.1194/jlr.R500016-JLR200. PMID 16339110.
• El Oualid F, Cohen LH, van der Marel GA, Overhand M (2006). "Inhibitors of protein: geranylgeranyl transferases". Curr. Med. Chem. 13 (20): 2385–427. doi:10.2174/092986706777935078. PMID 16918362.

• Genes on human chromosome 8
• Genes on human chromosome 5