COLL 137 |
| Kathy Boesze-Battaglia, G. Harrison, S.C. Clayton, C. Gretzula R.J. Schimmel, and Ellis Golub. Dept. of Biochemistry, School of Dental Medicine University of Pennsylvania, 4001 Spruce Street, Philadelphia, PA 19104 |
| Platelets contain a cholesterol, sphingomyelin enriched membrane microdomain known colloquially as a raft. In the presence of aggregatory stimuli platelets change shape from smooth disc to a spiny sphere. This shape change implies a reorganization of membrane lipid components to accommodate or drive the shape change. In these studies we investigated if cholesterol redistributes in response to aggregators. Fluorescent analogs of cholesterol and enzymatic oxidation by cholesterol oxidase were used to probe the stimulus dependent redistribution of this lipid in platelet plasma membranes. When resting platelets were treated with collagen or ADP, a substantial fraction of the cell surface cholesterol became inaccessible to quenching or oxidation within 2minutes, implying a redistribution of this lipid, either laterally or to the inner membrane monolayer. In platelets this translocation was uni-directional. We have expanded these studies to ask what role cholesterol enriched membrane microdoamins play in chondrogenesis, another biological process driven by shape change to facilitate the formation of matrix vesicles. The stimulus dependent reorganization of cholesterol suggests that cholesterol enriched membrane microdomains likely rearrange in response to the physiological needs of the cell. |
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Bio-Colloids
2:00 PM-4:30 PM, Monday, March 29, 2004 Marriott -- Grand Ballroom K, Oral
Division of Colloid and Surface Chemistry |