17 August 1994 Fluorescence energy transfer studies on the macrophage scavenger receptor
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The macrophage scavenger receptor is a transmembrane, trimeric glycoprotein which recognizes a number of negatively charged ligands. Cross competition studies of various ligands indicate that the scavenger receptor may bear more than one type of binding site or that there may be more than one type of receptor. In this study we employed resonance energy transfer techniques to identify the location of the binding site for maleylated bovine serum albumin. Using vesicles derived from plasma membrane, we labeled the ligand with a donor probe and labeled the membrane surface with acceptor probes to determine the distance of bound ligand from the membrane surface. Measurements were taken with three different donor-acceptor pairs. Transfer measurements for ligand labeled with dansyl and HAE (hexadecanoylaminoeosin) as the acceptor yielded a distance of 47 angstrom from the surface of the plasma membrane. Similar measurements employing the same donors but using ORB (octadecylrhodamine B) as the acceptor produced a distance of 58 angstrom. Assuming that the receptor extends perpendicularly from the cell surface this distance lies within the two receptor `domains' closest to the cell surface. These domains include the spacer region, with no distinct proposed structure and a region which has sequence similarity to an alpha helical coiled coil. No transfer was observed between ligand monolabeled with fluorescein and DiI in the membrane. This suggests that the orientation of mal-BSA bound to receptor places the fluorescein probe too far from acceptor on the membrane surface to experience energy transfer.
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Angelique Y. Louie, Angelique Y. Louie, Bruce J. Tromberg, Bruce J. Tromberg, Michael W. Berns, Michael W. Berns, } "Fluorescence energy transfer studies on the macrophage scavenger receptor", Proc. SPIE 2134, Laser-Tissue Interaction V; and Ultraviolet Radiation Hazards, (17 August 1994); doi: 10.1117/12.182935; https://doi.org/10.1117/12.182935

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