Macrophage scavenger receptor 1, also known as MSR1, is a protein which in humans is encoded by the MSR1 gene. [5] [6] MSR1 has also been designated CD204 (cluster of differentiation 204).
Macrophage scavenger receptor 1, also known as MSR1, is a protein which in humans is encoded by the MSR1 gene. [5] [6] MSR1 has also been designated CD204 (cluster of differentiation 204).
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 trimeric integral membrane glycoproteins and have been implicated in many macrophage-associated physiological and pathological processes including atherosclerosis, 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. [7]
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. [5]
Macrophage scavenger receptor has been shown to mediate adhesion of macrophages and other cell lines to tissue culture plastic. [8]
Scavenger receptors are a large and diverse superfamily of cell surface receptors. Its properties were first recorded in 1970 by Drs. Brown and Goldstein, with the defining property being the ability to bind and remove modified low density lipoproteins (LDL). Today scavenger receptors are known to be involved in a wide range of processes, such as: homeostasis, apoptosis, inflammatory diseases and pathogen clearance. Scavenger receptors are mainly found on myeloid cells and other cells that bind to numerous ligands, primarily endogenous and modified host-molecules together with pathogen-associated molecular patterns(PAMPs), and remove them. The Kupffer cells in the liver are particularly rich in scavenger receptors, includes SR-A I, SR-A II, and MARCO.
Apolipoprotein B (ApoB) is a protein that in humans is encoded by the APOB gene. It is commonly used to detect risk of atherosclerotic cardiovascular disease.
The activin A receptor also known as ACVR1C or ALK-7 is a protein that in humans is encoded by the ACVR1C gene. ACVR1C is a type I receptor for the TGFB family of signaling molecules.
Complement receptor type 2 (CR2), also known as complement C3d receptor, Epstein-Barr virus receptor, and CD21, is a protein that in humans is encoded by the CR2 gene.
Midkine, also known as neurite growth-promoting factor 2 (NEGF2), is a protein that in humans is encoded by the MDK gene.
Acetyl-CoA acetyltransferase, mitochondrial, also known as acetoacetyl-CoA thiolase, is an enzyme that in humans is encoded by the ACAT1 gene.
Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family of proteins that in humans is encoded by the HBEGF gene.
Oxidized low-density lipoprotein receptor 1 also known as lectin-type oxidized LDL receptor 1 (LOX-1) is a protein that in humans is encoded by the OLR1 gene.
Deleted in malignant brain tumors 1 protein is a protein that in humans is encoded by the DMBT1 gene.
CD47 also known as integrin associated protein (IAP) is a transmembrane protein that in humans is encoded by the CD47 gene. CD47 belongs to the immunoglobulin superfamily and partners with membrane integrins and also binds the ligands thrombospondin-1 (TSP-1) and signal-regulatory protein alpha (SIRPα). CD-47 acts as a don't eat me signal to macrophages of the immune system which has made it a potential therapeutic target in some cancers, and more recently, for the treatment of pulmonary fibrosis.
Low-density lipoprotein receptor-related protein 6 is a protein that in humans is encoded by the LRP6 gene. LRP6 is a key component of the LRP5/LRP6/Frizzled co-receptor group that is involved in canonical Wnt pathway.
Interferon regulatory factor 5 is a protein that in humans is encoded by the IRF5 gene. The IRF family is a group of transcription factors that are involved in signaling for virus responses in mammals along with regulation of certain cellular functions.
CD166 antigen is a 100-105 kD typeI transmembrane glycoprotein that is a member of the immunoglobulin superfamily of proteins. In humans it is encoded by the ALCAM gene. It is also called CD166, MEMD, SC-1/DM-GRASP/BEN in the chicken, and KG-CAM in the rat.
Interleukin 11 receptor, alpha subunit is a subunit of the interleukin 11 receptor. IL11RA is its human gene.
Lipid phosphate phosphohydrolase 1 also known as phosphatidic acid phosphatase 2a is an enzyme that in humans is encoded by the PPAP2A gene.
Protein UXT also known as androgen receptor trapped clone 27 (ART-27) protein is a protein that in humans is encoded by the UXT gene.
Stabilin-1 is a protein that in humans is encoded by the STAB1 gene.
E3 ubiquitin-protein ligase RNF14 is an enzyme that in humans is encoded by the RNF14 gene.
Macrophage receptor with collagenous structure (MARCO) is a protein that in humans is encoded by the MARCO gene. MARCO is a class A scavenger receptor that is found on particular subsets of macrophages. Scavenger receptors are pattern recognition receptors (PRRs) found most commonly on immune cells. Their defining feature is that they bind to polyanions and modified forms of a type of cholesterol called low-density lipoprotein (LDL). MARCO is able to bind and phagocytose these ligands and pathogen-associated molecular patterns (PAMPs), leading to the clearance of pathogens and cell signaling events that lead to inflammation. As part of the innate immune system, MARCO clears, or scavenges, pathogens, which leads to inflammatory responses. The scavenger receptor cysteine-rich (SRCR) domain at the end of the extracellular side of MARCO binds ligands to activate the subsequent immune responses. MARCO expression on macrophages has been associated with tumor development and also with Alzheimer's disease, via decreased responses of cells when ligands bind to MARCO.
Cathepsin F is a protein that in humans is encoded by the CTSF gene.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.