MSR1

Macrophage scavenger receptor 1, also known as MSR1, is a is_associated_with::protein which in humans is encoded by the MSR1 is_associated_with::gene.

MSR1 has also recently been designated CD204 (is_associated_with::cluster of differentiation 204).

Function
This gene encodes the class A is_associated_with::macrophage is_associated_with::scavenger receptors, which include three different types (1, 2, 3) generated by alternative splicing of this gene. These receptors or isoforms are trimeric integral membrane is_associated_with::glycoproteins and have been implicated in many macrophage-associated physiological and pathological processes including atherosclerosis, is_associated_with::Alzheimer's disease, and host defense. They were thought to be expressed macrophage-specific, but recently shown to be present on different dendritic cells classes, too.

The isoforms type 1 and type 2 are functional receptors and are able to mediate the endocytosis of modified is_associated_with::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 is_associated_with::endoplasmic reticulum, making it unable to perform is_associated_with::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.

Biotechnology application
Macrophage scavenger receptor has been shown to mediate adhesion of macrophages and other cell lines to tissue culture plastic.

Interactions
MSR1 has been shown to interact with is_associated_with::HSPA1A.