title: Restricted diffusion of integral membrane proteins and polyphosphoinositides leads to their depletion in microvesicles released from human erythrocytes.
abstract: The protein and phospholipid composition of microvesicles released from normal human erythrocytes after ATP depletion, on aging or by treatment with merocyanine 540, dimyristoyl phosphatidylcholine or Ca2+/ionophore A23187 has been compared with the composition of the original cell membrane. It has been shown that these microvesicles are depleted of band 3, glycophorin and phosphatidylinositol 4,5-bisphosphate relative to phospholipid by 40% or more. These data are interpreted to mean that less than half of these membrane components are free to diffuse laterally in the lipid bilayer. Acetylcholinesterase was found to be enriched 2-3-fold in microvesicles, possibly because the removal of non-diffusing proteins from the vesiculating region of the lipid bilayer allows more space for freely diffusing proteins like acetylcholinesterase to enter the microvesicle membrane.
authors.affiliation: Department of Physiology, University College and Middlesex School of Medicine, London, U.K.
authors.forename: C
authors.initials: C
authors.lastname: Hagelberg
authors.forename: D
authors.initials: D
authors.lastname: Allan
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D004058:Diffusion; D004134:Dimyristoylphosphatidylcholine / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008051:Lipid Bilayers / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000097:blood*; D011744:Pyrimidinones / Q000494:pharmacology; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D008051:Lipid Bilayers; D008055:Lipids; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D011744:Pyrimidinones; D011838:Radiation-Sensitizing Agents; D000001:Calcimycin; C003954:merocyanine dye; D002118:Calcium; D004134:Dimyristoylphosphatidylcholine