TAILIEUCHUNG - Báo cáo khoa học: Separation and characterization of caveolae subclasses in the plasma membrane of primary adipocytes; segregation of specific proteins and functions

Caveolae are nearly ubiquitous plasma membrane domains that in adipo-cytes vary in size between 25 and 150 nm. They constitute sites of entry into the cell as well as platforms for cell signalling. We have previously reported that plasma membrane-associated caveolae that lack cell surface access can be identified by electron microscopy. | ềFEBS Journal Separation and characterization of caveolae subclasses in the plasma membrane of primary adipocytes segregation of specific proteins and functions Unn Ortegren1 Lan Yin1 Anita Ost1 Helen Karlsson2 Fredrik H. Nystrom3 and Peter Stralfors1 1 Department of Cell Biology and Diabetes Research Centre University of Linkoping Sweden 2 Department of Molecular and ClinicalMedicine University of Linkoping Sweden 3 Department of Medicine and Care and Diabetes Research Centre University of Linkoping Sweden Keywords cholesterol FATP GLUT4 insulin receptorSR-BI Correspondence P. Stralfors Department of Cell Biology Faculty of Health Sciences SE58185 Linkoping Sweden Fax 46 13 224314 Tel 46 13 224315 E-mail Received 7 April2006 revised 27 April 2006 accepted 26 May 2006 doi Caveolae are nearly ubiquitous plasma membrane domains that in adipocytes vary in size between 25 and 150 nm. They constitute sites of entry into the cell as well as platforms for cell signalling. We have previously reported that plasma membrane-associated caveolae that lack cell surface access can be identified by electron microscopy. We now report the identification after density gradient ultracentrifugation of a subclass of very high-density apparently closed caveolae that were not labelled by cell surface protein labelling of intact cells. These caveolae contained caveolin-1 and caveolin-2. Another class of high-density caveolae contained caveolin-1 caveolin-2 and specifically fatty acid transport protein-1 fatty acid transport protein-4 fatty acyl-CoA synthetase hormone-sensitive lipase perilipin and insulin-regulated glucose transporter-4. This class of caveolae was specialized in fatty acid uptake and conversion to triacylglycerol. A third class of low-density caveolae contained the insulin receptor class B scavenger receptor-1 and insulin-regulated glucose transporter-4. Small amounts of these proteins were also detected in the .

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