Geranylgeranylation
Encyclopedia
Geranylgeranylation is a form of prenylation
, which is a post-translational modification of proteins that involves the attachment of one or two 20-carbon lipophilic geranylgeranyl isoprene
units from geranylgeranyl diphosphate to one or two cysteine
residue(s) at the C-terminus of specific proteins. Prenylation (including geranylgeranylation) is thought to function, at least in part, as a membrane anchor for proteins.
The process of geranylgeranylation can be catalyzed by either geranylgeranyl transferase I
(GGTase I) or Rab GGTase
(also GGTase II). GGTase I catalyzes the addition of one geranylgeranyl group onto the C-terminal consensus sequence CAAL (somewhat similar to farnesyltransferase reactions), where C=cysteine, A=any aliphatic amino acid, and L=leucine. Rab GGTase adds a total of two geranylgeranyl groups onto two cysteine residues at the C-terminal consensus sequence CXC or XXCC. The source of the geranylgeranyl group is geranylgeranyl diphosphate, which is synthesized from the isoprenoid biosynthetic pathway.
An example of this can be seen in the lipid anchoring of the Rho GTPase family of signaling molecule
s and the gamma subunit of heterotrimeric G proteins.
For more information see prenylation
.
Prenylation
Prenylation, or isoprenylation, or lipidation is the addition of hydrophobic molecules to a protein. It is usually assumed that prenyl groups facilitate attachment to cell membranes, similar to lipid anchor like the GPI anchor, though direct evidence is missing...
, which is a post-translational modification of proteins that involves the attachment of one or two 20-carbon lipophilic geranylgeranyl isoprene
Isoprene
Isoprene , or 2-methyl-1,3-butadiene, is a common organic compound with the formula CH2=CCH=CH2. Under standard conditions it is a colorless liquid...
units from geranylgeranyl diphosphate to one or two cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
residue(s) at the C-terminus of specific proteins. Prenylation (including geranylgeranylation) is thought to function, at least in part, as a membrane anchor for proteins.
The process of geranylgeranylation can be catalyzed by either geranylgeranyl transferase I
Geranylgeranyltransferase type 1
Geranylgeranyltransferase type 1 or simply geranylgeranyltransferase is one of the three enzymes in the prenyltransferase group. In specific terms, Geranylgeranyltransferase adds a 20-carbon isoprenoid called a geranylgeranyl group to proteins bearing a CaaX motif: a four-amino acid sequence at...
(GGTase I) or Rab GGTase
Rab geranylgeranyltransferase
Rab geranylgeranyltransferase also known as geranylgeranyltransferase II is one of the three prenyltransferases. It transfers two geranylgeranyl groups to the cystein at the C-terminus of Rab proteins....
(also GGTase II). GGTase I catalyzes the addition of one geranylgeranyl group onto the C-terminal consensus sequence CAAL (somewhat similar to farnesyltransferase reactions), where C=cysteine, A=any aliphatic amino acid, and L=leucine. Rab GGTase adds a total of two geranylgeranyl groups onto two cysteine residues at the C-terminal consensus sequence CXC or XXCC. The source of the geranylgeranyl group is geranylgeranyl diphosphate, which is synthesized from the isoprenoid biosynthetic pathway.
An example of this can be seen in the lipid anchoring of the Rho GTPase family of signaling molecule
Signaling molecule
A signaling molecule is a chemical involved in transmitting information between cells. Such molecules are released from the cell sending the signal, cross over the gap between cells by diffusion, and interact with specific receptors in another cell, triggering a response in that cell by activating...
s and the gamma subunit of heterotrimeric G proteins.
For more information see prenylation
Prenylation
Prenylation, or isoprenylation, or lipidation is the addition of hydrophobic molecules to a protein. It is usually assumed that prenyl groups facilitate attachment to cell membranes, similar to lipid anchor like the GPI anchor, though direct evidence is missing...
.