Type I macrophage scavenger receptor contains alpha-helical and collagen-like coiled coils
Article Abstract:
Numerous macrophages are found within the arterial fatty plaques characteristic of atherosclerosis. The macrophages are so laden with ingested fatty droplets that their appearance has earned them the name 'foam cells'. These foam cells are suspected of playing a role in the development of atherosclerosis, and now new insights have been obtained into the mechanism by which the macrophages recognize the low-density lipoproteins which seem to be in need of scavenging. It has been reported that receptors on the surface of the macrophage recognize low-density lipoproteins (LDLs) which have been modified by acetylation or oxidation. Molecular biological techniques have revealed that the scavenger receptor on the macrophage has some interesting structural features. DNA sequencing techniques have revealed the gene sequence for the scavenger receptor; this can be used to determine the likely amino acid sequence. This amino acid sequence can then be compared to vast quantities of information already obtained on the relationship of amino acid sequence to three-dimensional structure. When this is done with the scavenger receptor, it is observed that the receptor is similar to the protein collagen which occurs in ligaments, bone, joints, and numerous other tissues. The receptor probably exists as an interwoven set of three individual protein chains on the cell surface; it is known that this receptor has a broad spectrum of affinities. The roles of this receptor in normal physiology and the development of atherosclerosis have not yet been elucidated. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1990
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Coiled-coil fibrous domains mediate ligand binding by macrophage scavenger receptor type II
Article Abstract:
The scavenger receptors are thought to play a key role in the development of atherosclerosis. These molecules, located on macrophages, bind to the low-density lipoprotein (LDL) in atherosclerotic plaques. Techniques of gene cloning and sequencing have recently predicted the molecular structure of type I scavenger receptors. The protein seems to consist of three regions, any of which might be the actual location of the binding of LDL. The structure of the type II scavenger receptor molecule is very similar, but has only two of the three major regions. Since the binding properties of the type II receptor are very similar to those of type I, the binding is likely to be achieved in one of the regions which the two molecules have in common. Both of these regions have a structure consisting of coils of coils, similar to those observed in collagen. The coiled-coil domains seem to be the location of the binding activity of the type II receptor. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1990
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A role for macrophage scavenger receptors in atherosclerosis and susceptibility to infection
Article Abstract:
Targeted disruption of the macrophage type-I and type-II class-A scavenger receptors (MSR-A) gene in mice results in size reduction of atherosclerotic lesions in an animal deficient in apolipoprotein E. Macrophages from these deficient mice reveal a marked decrease in the in vitro uptake of modified low-density lipoproteins (mLDL), whereas mLDL clearance from plasma occurs at a normal rate. This indicates that alternative mechanisms for removing mLDL from the circulation exist. MSR-A may also play a role in host defense against pathogens.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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