Glycosyl-phosphatidylinositol anchored membrane enzymes.
Several mammalian enzymes are anchored to the outer surface of the plasma membrane by a covalently attached glycosyl-phosphatidylinositol (GPI) structure. These include acetylcholinesterase, alkaline phosphatase, membrane dipeptidase and 5'-nucleotidase. All GPI anchors determined to date have the conserved core structure ethanolamine-PO4-6Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcNH2 alpha 1-6myo-inositol-1-PO4- lipid. In most mammalian GPI anchors the lipid is 1-alkyl-2-acyl-glycerol, although in porcine membrane dipeptidase it is diacylglycerol. Attached to the conserved core are various side chain residues that appear to be either protein- or tissue-specific. In addition to membrane attachment, a GPI anchor may confer additional properties on the protein, such as the susceptibility to cleavage by phospholipases and the potential to cluster in detergent-insoluble domains. GPI anchors can also act as intracellular targeting signals, in transmembrane signalling, in the clathrin-independent endocytic process of potocytosis and as hormone mediators. Thus, a GPI anchor can confer additional properties on enzymes that may be important in their physiological and pathophysiological functioning.
Hooper
N M
NM
School of Biochemistry and Molecular Biology, University of Leeds, UK. n.m.hooper@leeds.ac.uk
D015720:5'-Nucleotidase / Q000378:metabolism*; D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D002236:Carbohydrate Conformation; D004150:Dipeptidases / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D013552:Swine
D017261:Glycosylphosphatidylinositols; D000110:Acetylcholinesterase; D015720:5'-Nucleotidase; D004150:Dipeptidases; C038937:dipeptidase