High Quality Content by WIKIPEDIA articles! Prenylation, or isoprenylation, or lipidation is the addition of hydrophobic molecules to a protein. It is usually assumed that prenyl groups (3-methyl-2-buten-1-yl) facilitate attachment to cell membranes, similar to lipid anchor like the GPI anchor, though direct evidence is missing. Prenyl groups have been shown to be important for protein-protein binding through specialized prenyl-binding domains.