Depalmitoylation of CAAX motif proteins. Protein structural determinants of palmitate turnover rate.
In the present study, we examined the effect of amino acid substitutions on the rate of turnover of palmitate bound to a model "CAAX" motif protein H-Ras. These experiments were designed to shed light on the specificity of the process that removes palmitate from prenylated proteins. H-Ras, protein A-Ras fusion constructs, and constructs with amino acid substitutions in the H-Ras hypervariable region were transfected into COS cells, and the turnover rate of palmitate bound to each expressed protein was measured. We found no evidence for strict sequence specificity for palmitate removal, but found a strong inverse correlation between palmitate turnover rate and the degree of membrane association for any given construct, with slower turnover rates associated with stronger membrane binding. These data support a model in which the palmitate turnover rate is determined by access to a depalmitoylating enzyme and argue against a more complex model in which specific recognition of palmitoylated proteins is required.
Lu
J Y
JY
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Hofmann
S L
SL
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D017931:DNA Primers; D007668:Kidney; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015689:Oncogene Protein p21(ras) / Q000737:chemistry / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D014162:Transfection; D018631:ras Proteins / Q000737:chemistry / Q000378:metabolism*
D017931:DNA Primers; D010169:Palmitic Acids; D011993:Recombinant Fusion Proteins; D019308:Palmitic Acid; D015689:Oncogene Protein p21(ras); D018631:ras Proteins