salkenylcysteines

Salkenylcysteines are a class of modified amino acids that are formed by the attachment of a long-chain unsaturated fatty acid (alkene) to the sulfur atom of the cysteine residue. This modification, known as prenylation or isoprenylation, is a type of lipidation. The alkenyl group is typically derived from isopentenyl pyrophosphate or dimethylallyl pyrophosphate.

These modified cysteine residues are often found at or near the C-terminus of proteins. The presence of the hydrophobic alkenyl chain can significantly alter the protein's properties, influencing its localization within cellular membranes, its interaction with other proteins, and its overall biological activity. Salkenylcysteines are particularly important in the signaling pathways of eukaryotic cells.

The attachment of the alkenyl group is catalyzed by enzymes called prenyltransferases. This post-translational modification is reversible in some cases, allowing for dynamic regulation of protein function. Proteins containing salkenylcysteines play roles in various cellular processes, including cell growth, differentiation, and signal transduction. Examples of proteins that undergo this modification include members of the Ras superfamily of small GTPases, which are critical regulators of cell signaling.