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Isolation and characterization of two distinct low-density, Triton-insoluble, complexes from porcine lung membranes

Parkin, Edward and Turner, A J and Hooper, N M (1996) Isolation and characterization of two distinct low-density, Triton-insoluble, complexes from porcine lung membranes. Biochemical Journal, 319 (3). pp. 887-896. ISSN 0264-6021

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Abstract

The Triton-insoluble complex from porcine lung membranes has been separated into two distinct subfractions visible as discrete light-scattering bands following buoyant density-gradient centrifugation in sucrose. Both of these detergent-insoluble complexes were enriched in the glycosyl-phosphatidylinositol (GPI)-anchored ectoenzymes alkaline phosphatase, aminopeptidase P and 5'-nucleotidase, and both complexes excluded the polypeptide-anchored ectoenzymes angiotensin-converting enzyme, dipeptidyl peptidase IV and aminopeptidases A and N. The GPI-anchored proteins in both complexes were susceptible to release by phosphatidylinositol-specific phospholipase C. Both complexes were also enriched in cholesterol and glycosphingolipids, and in caveolin/VIP21, although only the higher-density fraction was enriched in the plasmalemmal caveolar marker proteins Ca(2+)-ATPase and the inositol 1,4,5-trisphosphate receptor. Among the annexin family of proteins, annexins I and IV were absent from the two detergent-insoluble complexes, annexin V was present in both, and annexins II and VI were only enriched in the higher-density fraction. When the mental chelator EGTA was present in the isolation buffers, annexins II and VI dissociated from the higher-density detergent-insoluble complex and only a single light-scattering band was observed on the sucrose gradient, at the same position as for the lower-density complex. In contrast, in the presence of excess calcium only a single detergent-insoluble complex was isolated from the sucrose gradients, at an intermediate density. Thus the detergent-insoluble membrane complex can be subfractionated on the basis of what appears to be calcium-dependent, annexin-mediated, vesicle aggregation into two distinct populations, only one of which is enriched in plasmalemmal caveolar marker proteins.

Item Type: Article
Journal or Publication Title: Biochemical Journal
Uncontrolled Keywords: 5'-Nucleotidase ; Alkaline Phosphatase ; Aminopeptidases ; Animals ; Annexins ; Antigens, CD13 ; Cell Membrane ; Centrifugation, Density Gradient ; Cholesterol ; Dipeptidyl Peptidase 4 ; Fatty Acids, Nonesterified ; Glutamyl Aminopeptidase ; Glycosylphosphatidylinositols ; Intracellular Membranes ; Lung ; Membrane Lipids ; Microsomes ; Peptidyl-Dipeptidase A ; Phospholipids ; Polyethylene Glycols ; Solubility ; Swine
Subjects:
Departments: Faculty of Health and Medicine > Biomedical & Life Sciences
ID Code: 51854
Deposited By: ep_importer_pure
Deposited On: 06 Dec 2011 16:45
Refereed?: Yes
Published?: Published
Last Modified: 09 Apr 2014 22:55
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/51854

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