
**NCBI Gene Summary**: This gene encodes the class A macrophage scavenger receptors, which include three different types (1, 2, 3) generated by alternative splicing of this gene. These receptors or isoforms are macrophage-specific trimeric integral membrane glycoproteins and have been implicated in many macrophage-associated physiological and pathological processes including atherosclerosis, Alzheimer's disease, and host defense. The isoforms type 1 and type 2 are functional receptors and are able to mediate the endocytosis of modified low density lipoproteins (LDLs). The isoform type 3 does not internalize modified LDL (acetyl-LDL) despite having the domain shown to mediate this function in the types 1 and 2 isoforms. It has an altered intracellular processing and is trapped within the endoplasmic reticulum, making it unable to perform endocytosis. The isoform type 3 can inhibit the function of isoforms type 1 and type 2 when co-expressed, indicating a dominant negative effect and suggesting a mechanism for regulation of scavenger receptor activity in macrophages. [provided by RefSeq, Jul 2008]

**GeneCards Summary**: MSR1 (Macrophage Scavenger Receptor 1) is a Protein Coding gene. Diseases associated with MSR1 include Barrett Esophagus and Polycystic Ovary Syndrome. Among its related pathways are Binding and Uptake of Ligands by Scavenger Receptors and Vesicle-mediated transport. Gene Ontology (GO) annotations related to this gene include DNA-binding transcription factor activity and scavenger receptor activity. An important paralog of this gene is SCARA5.

**UniProtKB/Swiss-Prot Summary**: Membrane glycoproteins implicated in the pathologic deposition of cholesterol in arterial walls during atherogenesis. Two types of receptor subunits exist. These receptors mediate the endocytosis of a diverse group of macromolecules, including modified low density lipoproteins (LDL) [PMID: 2251254]. Isoform III does not internalize acetylated LDL [PMID: 9548586].
