Analysis of Protein Palmitoylation
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The incorporation of many membrane proteins into the lipid environment is based on sequences of largely hydrophobic amino acids that can form membrane-spanning domains. However, a number of other proteins are membrane-associated, but do not display such hydrophobic elements within their primary sequence. Membrane association in these cases is often provided by covalent attachment, either cotranslationally or posttranslationally, of lipid groups to the polypeptide chain. Acylation of proteins by either addition of C14:0 myristic acid to an N-terminal glycine residue or addition of C16:0 palmitic acid by thioester linkage to cysteine residues, in a variety of positions within the primary sequence, has been recorded for a wide range of proteins. Palmitoylation of proteins is not restricted to thioester linkage and may occur also through oxyester linkages to serine and threonine residues. Furthermore, thioester linkage of fatty acyl groups to proteins is not restricted to palmitate. Longer chain fatty acids, such as stearic acid (C18:0) and arachidonic acid (C20:4), have also been detected. Artificial peptide studies have provided evidence to support the concept that attachment of palmitate to a protein can provide sufficient binding energy to anchor a protein to a lipid bilayer, but that attachment of myristate is insufficient, in isolation, to achieve this.
KeywordsPalmitic Acid Myristic Acid Dialysis Tubing Membrane Association Newborn Calf Serum