The MAL proteolipid is a component of the detergent-insoluble membrane subdomains of human T-lymphocytes

摘要: The human mal gene, identified during a search for cDNAs selectively expressed T-cell development, encodes highly hydrophobic protein belonging to group of proteins, termed proteolipids, characterized by their unusual property being soluble in organic solvents used extract cell lipids. To study the localization MAL we have prepared stable transfectants expressing tagged with c-myc epitope (MAL/c-myc) using epithelial A-498 cells. Immunofluorescence analysis suggested that MAL/c-myc is localized mainly cholesterol-enriched structures post-Golgi location and, at low levels, early endosomes. Moreover, extraction membranes Triton X-100 (TX100) and fractionation centrifugation equilibrium sucrose gradients demonstrated presence detergent-insoluble buoyant fraction, known be enriched glycolipids cholesterol. compare behaviour T-cells cells, stably transfected cells Jurkat T-cells. When TX100 extracts from were subjected found exclusively floating fractions, together molecules characteristic insoluble complexes, such as tyrosine kinase p56lck, glycosylphosphatidylinositol-anchored CD59 ganglioside GM1. These results, taken together, indicate proteolipid component detergent-resistant membrane microdomains present T-lymphocytes, suggest might play role modulating function these differentiation.