- Palmitoylation
S-Palmitoylation is the covalent attachment of fatty acids, such as
palmitic acid , tocysteine residues of membrane proteins. [ Linder, M.E., "Reversible modification of proteins with thioester-linked fatty acids," "Protein Lipidation", F. Tamanoi and D.S. Sigman, eds., pp. 215-40 (San Diego, CA: Academic Press, 2000).]The precise function of palmitoylation depends on the particular protein being considered. Palmitoylation enhances the hydrophobicity of proteins and contributes to their membrane association. Palmitoylation also appears to play a significant role in subcellular trafficking of proteins between membrane compartments, as well as in modulating
protein-protein interactions . [ Basu, J., "Protein palmitoylation and dynamic modulation of protein function," "Current Science", Vol. 87, No. 2, pp. 212-17 (25 July 2004), http://www.ias.ac.in/currsci/jul252004/contents.htm ] In contrast toprenylation andmyristoylation , palmitoylation is reversible. This allows the cell to dynamically regulate the location of specific proteins.An example of a protein that undergoes palmitoylation is
hemagglutinin , a membrane glycoprotein used byinfluenza to attach to host cell receptors. [ influenza viruses, the encyclopedia of virology, http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7GG4-4CK7DHD-S&_rdoc=5&_hierId=42642&_refWorkId=141&_explode=42642&_alpha=I&_fmt=full&_orig=na&_docanchor=&_idxType=AR&view=c&_ct=10&_acct=C000011279&_version=1&_urlVersion=0&_userid=5399531&md5=607bbb1a7d18138457365550b9471eb5. ]Because S-palmitoylation is a dynamic, post-translational process, it is believed to be employed by the cell to alter the subcellular localization,
protein-protein interaction s, or binding capacities of a protein.The palmitoylation cycles of a wide array of
enzyme s have been characterized in the past few years, includingH-Ras ,Gsα , theβ2-adrenergic receptor , and endothelialnitric oxide synthase (eNOS).Palmitoylation in Synaptic Plasticity
Recently, scientist have appreciated the significance of attaching long hydrophobic chains to specific proteins in cell signaling pathways. A good example of its significance is in the clustering of proteins in the synapse. A major mediator of protein clustering in the synapse is the postsynaptic density (95kD) protein,
PSD-95 . When this protein is palmitoylated it is restricted to the membrane. This restriction to the membrane allows it to bind to and cluster ion channels in thepostsynaptic membrane. Also, in the presynaptic neuron, palmitoylation ofSNAP-25 allows theSNARE complex to dissociate during vesicle fusion. This provides a role for palmitoylation in regulatingneurotransmitter release. ["Molecular Mechanisms of Synaptogenesis." Edited by Alexander Dityatev and Alaa El-Husseini. Springer: New York, NY. 2006. pg. 72-75]References
*Smotrys J and Linder A. (2004) [http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.biochem.73.011303.073954?cookieSet=1&journalCode=biochem "Palmitoylation of Intracellular Signaling Proteins: Regulation and Function"] . Annu Rev Biochem 73:559-87.
*Resh, M. (2006) [http://stke.sciencemag.org/cgi/content/abstract/2006/359/re14 "Palmitoylation of Ligands, Receptors, and Intracellular Signaling Molecules"] . Sci STK. 359 October 31.
*Linder M and Deschenes R. (2007) Palmitoylation: policing protein stability and traffic. Nature 8: 74-84.
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