Document Detail


The MAL proteolipid is a component of the detergent-insoluble membrane subdomains of human T-lymphocytes.
MedLine Citation:
PMID:  9003426     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The human mal gene, identified during a search for cDNAs selectively expressed during T-cell development, encodes a highly hydrophobic protein belonging to a group of proteins, termed proteolipids, characterized by their unusual property of being soluble in organic solvents used to extract cell lipids. To study the localization of the MAL protein we have prepared stable transfectants expressing the MAL protein tagged with a c-myc epitope (MAL/c-myc) using human epithelial A-498 cells. Immunofluorescence analysis suggested that MAL/c-myc is localized mainly to cholesterol-enriched structures with a post-Golgi location and, at low levels, in early endosomes. Moreover, extraction of A-498 cell membranes with Triton X-100 (TX100) and fractionation by centrifugation to equilibrium in sucrose gradients demonstrated the presence of MAL/c-myc in the detergent-insoluble buoyant fraction, known to be enriched in glycolipids and cholesterol. To compare the behaviour of MAL in T-cells with that in epithelial A-498 cells, we prepared stably transfected cells expressing MAL/c-myc using human Jurkat T-cells. When TX100 extracts from Jurkat cells were subjected to centrifugation to equilibrium in sucrose gradients we found MAL exclusively in the floating fractions, together with molecules characteristic of the T-cell insoluble complexes, such as the tyrosine kinase p56lck, the glycosylphosphatidylinositol-anchored protein CD59 and the ganglioside GM1. These results, taken together, indicate that the MAL proteolipid is a component of the detergent-resistant membrane microdomains present in T-lymphocytes, and suggest that MAL might play a role in modulating the function of these microdomains during T-cell differentiation.
Authors:
J Millán; R Puertollano; L Fan; C Rancaño; M A Alonso
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  321 ( Pt 1)     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1997 Jan 
Date Detail:
Created Date:  1997-02-20     Completed Date:  1997-02-20     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  247-52     Citation Subset:  IM    
Affiliation:
Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Consejo Superior de Investigaciones Cientificas, Spain.
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MeSH Terms
Descriptor/Qualifier:
Animals
Blotting, Western
Carrier Proteins / chemistry*
Digitonin / pharmacology
Filipin / pharmacology
Humans
Jurkat Cells
Membrane Proteins / chemistry*
Membrane Transport Proteins*
Mice
Myelin Proteins*
Proteolipids / chemistry*
T-Lymphocytes / chemistry*
Transfection
Chemical
Reg. No./Substance:
0/Carrier Proteins; 0/MAL protein, T-cell; 0/Membrane Proteins; 0/Membrane Transport Proteins; 0/Myelin Proteins; 0/Proteolipids; 11024-24-1/Digitonin; 480-49-9/Filipin
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