The Plasma Membrane of Granular Cells from Pig Epidermis: Isolation and Lipid and Protein Composition
| Autor: | I.A. King, G M Gray, H J Yardley |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
Epidermis (botany)
Swine Membrane lipids Cell Membrane Proteins Epidermal cell differentiation Cell Biology Dermatology Lipids Biochemistry chemistry.chemical_compound Membrane chemistry Phosphatidylcholine Animals Centrifugation Sphingomyelin Molecular Biology Polyacrylamide gel electrophoresis Skin |
| Zdroj: | Journal of Investigative Dermatology. (2):131-135 |
| ISSN: | 0022-202X |
| DOI: | 10.1111/1523-1747.ep12546728 |
| Popis: | Granular cells from pig and human epidermis were homogenized using a Stansted cell disrupter and a plasma membrane fraction was isolated by differential and gradient density centrifugation. The preparation of membrane sheets was substantially free of contaminants as judged by electron microscopy. The proteins of the plasma membranes from pig granular cells were examined by polyacrylamide gel electrophoresis after solubilization in 2.5% sodium dodecylsulfate and 8 M urea. The proteins consisted mainly of 3 polypeptides of molecular weights 56,000, 52,000 and 50,000 together with small amounts of polypeptides with molecular weights of 81,000, 77,000 and 74,000. The composition of the plasma membrane protein was quite different from that of the fraction mainly of cells without membranes (2 major polypeptides, molecular weights 79,000 and 68,000) and from those of other subcellular fractions. Cholesterol (25% of total lipids), ceramides (13%) and fatty acids (14%) were the major neutral lipids in the plasma membranes. Glucosylceramides (11%), sphingomyelin (9%) and phosphatidylcholine (8%) were the major polar lipids. The plasma membranes contained proportionally twice as much sphingomyelin and much less hydrocarbon than the lipids from whole granular cells. The specific activities of the putative plasma membrane enzymes amino acid-2-naphthylamidase and phosphodiesterase were not increased relative to the homogenate. It is suggested that enzyme activity is an unreliable criterion for the purity of membrane preparations from granular cells as it is possible that the final stages of epidermal cell differentiation cause a loss of enzyme activity in the plasma membranes of a proportion of the heterogeneous population of granular cells. |
| Databáze: | OpenAIRE |
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