Isoprenylation, lipid anchors

Lipidation -acylation TV -myristoylation Myristoy-lation S-prenylation Prenylation Palmitoylation Isoprenylation GPI anchors Glypiation... 

PPCs Prenylation is the post-translational addition of 15- or 20-carbon isoprenyl lipids to the C-terminus of proteins. Prenylation is an irreverable modification that anchors proteins to the membrane fraction of cells. 

Isoprene chains are sometimes used as lipid anchors to fix molecules to membranes (see p. 214). Chlorophyll has a phytyl residue (1 = 4) as a lipid anchor. Coenzymes with isoprenoid anchors of various lengths include ubiquinone (coenzyme Q 1 = 6-10), plastoqui-none (1 = 9), and menaquinone (vitamin K 1 = 4-6). Proteins can also be anchored to membranes by isoprenylation. 

Many GPCRs contain one or more conserved cysteine residues within their C-terminal tails, which are modified by covalent attachment of palmitoyl or isoprenyl residues. The palmitoyl moiety is anchored in the lipid bilayer forming a fourth intracellular loop. There is evidence that palmitoylation of a GPCR is a dynamic process and may affect receptor desensitization. 

Thus, lipoproteins could be injected over the surface of a lipid covered SPR sensor in a detergent free buffer solution and showed spontaneous insertion into the artificial membrane.171 Again two hydro-phobic modifications are necessary for stable insertion into the lipid layer, whereas lipoproteins with a farnesyl group only dissociate significantly faster out of the membrane. Therefore the isoprenylation of a protein is sufficient to allow interaction with membraneous structures, while trapping of the molecule at a particular location requires a second hydrophobic anchor. Interaction between the Ras protein and its effector Raf-kinase depends on complex formation of Ras with GTP (instead of the Ras GDP complex, present in the resting cell). If a synthetically modified Ras protein with a palmi-... 

Davies, B.S., et al. (2009). Increasing the length of progerin s isoprenyl anchor does not worsen bone disease or survival in mice with Hutchinson-Gilford progeria syndrome. J Lipid Res 50 126-134. 

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