SR-I,II Scavenger R-AI, Scavenger R-AII
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Lineage Restricted Molecule
Type 2 glycoprotein
75 / 225

The major sites of scavenger receptors 1 and 2 expression are tissue macrophages.  Inflammatory stimuli upregulate the expression.  The scavenger receptor has been identified in atherosclerotic lesions of human tissues.

SR-I and II are a homotrimeric type 2 glycoproteins.  SR-1 is a member of the Group A scavenger receptor cysteine- rich (SRCR) superfamily.  It is not known if naturally occurring receptors are homotrimers or heterotrimers of type 1 and 2 proteins.  The bovine sequence was deteremined 1st and is 70% identical to the human sequence.  The mature type 1 receptor is comprised of 50 aa N-terminal cytoplasmic sequence, a 26 aa transmembrane sequence, a 75 aa sequence with no homology to other proteins, a 121 aa sequence predicted to have an a  helical coiled-coil structure, a 69 aa collagen-like domain, and a C-terminal SRCR domain.  The type 2 receptor is identical to the type 1 receptor to the end of the collagen-like sequence, but the C-terminal scavenger receptor domain is replaced by a 17 aa segment.  The 2 scavenger receptors are generated by alternative mRNA splicing.  The type 1 receptor has an overall structure similar to MARCO, both having a C-terminal SRCR domain.  The scavenger receptor has a shorter collagenous region than MARCO.

Cell Type Unreduced Reduced
220 kDa 77 kDa

Scavenger receptors 1 and 2 bind modified low density lipoproteins.  Both receptors have a similar broad specificity for polyanionic ligands including cell surface components of gram-positive and gram-negative bacteria.  There is evidence from mutagenesis studies for their ligand binding properties being located in the collagenous region.  Scavenger receptors 1 and 2 bind b-amyloid fibrils.

Roles in the clearance of microbes and damaged or apoptotic cells and in recirculation are postulated.


Database accession numbers

Revised June 25, 2008

Contact us: Webmaster |  509-335-9515 | Accessibility | Copyright | Policies
College of Veterinary Medicine Washington State University, Pullman, WA, 99164-7010 USA
Copyright 1995-2003 Washington State University