CD204/MSR1 Protein, Human (HEK293, His)

The CD204/MSR1 protein, encoded by this gene, is a class A macrophage scavenger receptor that comprises three different isoforms (type 1, type 2, and type 3) resulting from alternative splicing. These trimeric integral membrane glycoproteins are mainly expressed in macrophages and play crucial roles in various macrophage-associated physiological and pathological processes, such as atherosclerosis, Alzheimer's disease, and host defense. Both type 1 and type 2 isoforms function as receptors capable of internalizing modified low-density lipoproteins (LDLs). In contrast, the type 3 isoform, despite having the domain responsible for mediating endocytosis, is unable to internalize modified LDLs due to altered intracellular processing and retention within the endoplasmic reticulum. Interestingly, when co-expressed, the type 3 isoform can inhibit the function of type 1 and type 2 isoforms, indicating a dominant negative effect and suggesting a mechanism for regulating scavenger receptor activity in macrophages. Furthermore, this protein exhibits broad expression in various tissues, including lung and gall bladder, as well as 19 other tissues.