http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:10609 CD36/FAT is a transmembrane glycoprotein that functions in the cellular uptake of long-chain fatty acids and also as a scavenger receptor. As such it plays an important role in lipid homeostasis and, pathophysiologically, in the progression of type 2 diabetes and atherosclerosis. CD36 expression is tightly regulated at the levels of both transcription and translation. Here we show that its expression and location are also regulated post-translationally, by palmitoylation. Although palmitoylation of CD36 was not required for receptor maturation and cell surface expression, inhibition of palmitoylation either pharmacologically with cerulenin or by mutation of the relevant cysteines delayed processing at the ER and trafficking through the secretory pathway. The absence of palmitoylation also reduced the half life of the CD36 protein. Additionally, the CD36 palmitoylation mutant did not incorporate efficiently into lipid rafts, a site known to be required for its function of fatty acid uptake, and this reduced the efficiency of uptake of oxidized low density lipoprotein. These findings provide an added level of sophistication where translocation of CD36 to the plasma membrane may be physiologically regulated by palmitoylation. 2012-04-12T01:41:54.853Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1955 Clustering of the T cell integrin, LFA-1, at specialized regions of intercellular contact initiates integrin-mediated adhesion and downstream signaling, events that are necessary for a successful immunological response. But how clustering is achieved and sustained is not known. Here we establish that an LFA-1-associated molecule, PTA-1, is localized to membrane rafts and binds the carboxyl-terminal domain of isoforms of the actin-binding protein 4.1G. Protein 4.1 is known to associate with the membrane-associated guanylate kinase homologue, human discs large. We show that the carboxyl-terminal peptide of PTA-1 also can bind human discs large and that the presence or absence of this peptide greatly influences binding between PTA-1 and different isoforms of 4.1G. T cell stimulation with phorbol ester or PTA-1 cross-linking induces PTA-1 and 4.1G to associate tightly with the cytoskeleton, and the PTA-1 from such activated cells now can bind to the amino-terminal region of 4.1G. We propose that these dynamic associations provide the structural basis for a regulated molecular adhesive complex that serves to cluster and transport LFA-1 and associated molecules. 2011-05-03T00:10:16.959Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1051 CD36 is a transmembrane glycoprotein receptor that engages in signal transduction implicated in important physiological and pathophysiological events. CD36 in platelets has been shown physically and functionally to associate with members of the Src family of protein tyrosine kinases, Fyn, Lyn, and Yes, but the nature of this important association has never been rigorously examined. Here, we show that CD36 does not associate with Lyn through a protein-mediated interaction. In COS cells transfected with both CD36 and Lyn these molecules did not co-precipitate, suggesting a requirement for an intermediary molecule absent from the COS cells. Yeast two-hybrid analysis confirmed that the carboxylterminal cytoplasmic tail of CD36 did not bind Lyn directly, and no Lyn binding protein bound to CD36 in a cDNA library screen. Conversely, when the CD36–Lyn association seen in platelets was analysed by biophysical parameters, dissociation occurred at 37 °C and also by solubilisation in octylglucoside, indicative of a lipid-mediated association. Since both CD36 and Lyn are enriched in Triton X-100-insoluble rafts at the plasma membrane, these findings point to the importance of raft-associated lipids in CD36-mediated signal transduction. 2010-04-27T06:08:04.762Z ]]>