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farnesylation

Saturday 27 January 2018

Definition: Farnesylation is a type of prenylation , a post-translational modification of proteins by which an isoprenyl group is added to a cysteine residue.

It is an important process to mediate protein–protein interactions and protein–membrane interactions.

Protein farnesylation involves the transfer of a farnesyl moiety to C-terminal cysteine(s) of the target protein. There are enzymes that carry out this type of prenylation as farnesyl transferase.

Farnesyltransferase and Geranylgeranyltransferase I are very similar proteins. They consist of two subunits, the α-subunit, which is common to both enzymes, and the β-subunit, whose sequence identity is just 25%.

These enzymes recognise the CaaX box at the C-terminus of the target protein. C is the cysteine that is prenylated, a is any aliphatic amino acid, and the identity of X determines which enzyme acts on the protein.

Farnesyltransferase recognizes CaaX boxes where X = M, S, Q, A, or C, whereas Geranylgeranyltransferase I recognizes CaaX boxes with X = L or E.