The cytosolic proteins, Ras and Rab, are anchored to the cytosolic face of the plasma membrane by prenylation. Prenylation typically occurs at which amino acid of the protein?

Correct option is A

Correct Answer: Option 1
Explanation: Prenylation is a lipid modification in which isoprenoid groups (farnesyl or geranylgeranyl) are covalently attached to proteins such as Ras and Rab. This modification typically occurs on a cysteine residue near the C-terminus, often within a CAAX motif (where C = cysteine, A = aliphatic amino acid, X = determining residue). Prenylation increases hydrophobicity, enabling these proteins to associate with the cytosolic face of the plasma membrane.