Palmitoylation-dependent control of degradation, life span, and membrane expression of the CCR5 receptor

We have shown that the chemokine and HIV receptor CCR5 is palmitoylated on a cluster of cysteine residues located at the boundary between the seventh transmembrane region and the cytoplasmic tail. Single or combined substitut ions of the three cysteines (Cys-321, Cys-323, and Cys-324) or incubation o f wild-type CCR5-transfected cells with the palmitic acid analog 2-bromopal mitate prevented palmitoylation of the receptor. Moreover, failure of CCR5 to be palmitoylated resulted in both accumulation in intracellular stores a nd a profound decrease of membrane expression of the receptor. Upon metabol ic labeling, kinetic experiments showed that the half-life of palmitoylatio n-deficient CCR5 is profoundly decreased. Bafilomycin A1, but not a specifi c proteasome inhibitor, prevented early degradation of palmitoylation-defic ient CCR5 and promoted its accumulation in lysosomal compartments. Although membrane expression of the CCR5 mutant was diminished, the molecules reach ing the membrane were still able to interact efficiently with the chemokine ligand MIP1 beta and remained able to function as BW co-receptors. Thus we conclude that palmitoylation controls CCR5 expression through regulation o f the life span of this receptor.