ISSN:
1573-6830
Keywords:
acetylcholinesterase
;
glycolipid anchors
;
phosphatidylinositol-specific phospholipase C
;
alkylacylglycerol
;
diacylglycerol
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 1. We describe two simple procedures for the rapid identification of certain structural features of glycolipid anchors in acetylcholinesterases (AChEs). 2. Treatment with alkaline hydroxylamine (that cleaves ester-linked acyl chains but not ether-linked alkyl chains) converts molecules possessing adiacylglycerol, but not those with analkylacylglycerol, into hydrophilic derivatives. AChEs in human and bovine erythrocytes possess an alkylacylglycerol (Robertset al., J. Biol. Chem. 263:18766–18775, 1988;Biochem. Biophys. Res. Commun. 150:271–277, 1988) and are not converted to hydrophilic dimers by alkaline hydroxylamine. Amphiphilic dimers of AChE fromDrosophila, from mouse erythrocytes, and from the human erythroleukaemia cell line K562 also resist the treatment with hydroxylamine and likely possess a terminal alkylacylglycerol. This indicates that the cellular pool of free glycolipids used as precursors of protein anchors is distinct from the pool of membrane phosphatidylinositols (which contain diacylglycerols). 3. Pretreatment with alkaline hydroxylamine is required to render the amphiphilic AChE from human erythrocytes susceptible to digestion byBacillus thuringiensis phosphatidylinositol-specific phospholipase C (PI-PLC) (Toutantet al., Eur. J. Biochem. 180:503–508, 1989). We show here that this is also the case for the AChE from mouse erythrocytes, which therefore likely possesses an additional acyl chain in the anchor that prevents the action of PI-PLC. 4. In two sublines of K562 cells (48 and 243), we observed that AChE either was directly susceptible to PI-PLC (243) or required a prior deacylation by alkaline hydroxylamine (48). This suggests that glycolipid anchors in AChE of K562-48 cells, but not those in AChE of K562-243 cells, contain the additional acylation demonstrated in AChE from human erythrocytes. These observations illustrate the cell specificity (and the lack of species-specificity) of the structure of glycolipid anchors.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00712811
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