Scavenger receptor class A (SR-A (also known as SCARA1 or MSR1 for the prototypical member))

Scavenger receptor class A is a family of cell-surface receptors predominantly found on macrophages and related myeloid cells. They bind and internalize a broad spectrum of ligands, including modified lipoproteins (like acetylated and oxidized LDL), bacterial surface molecules, amyloid-β, heat shock proteins, and apoptotic cells. SR-A receptors play essential roles in host defense, lipid metabolism, inflammation, and clearance of cellular debris. Structurally, they are type II membrane proteins featuring a collagen-like domain critical for ligand binding and commonly form homotrimers at the cell surface. SR-A1 is the best-characterized, and its activity is linked to foam cell formation in atherosclerosis, pathogen clearance via phagocytosis, and modulation of the innate immune response. Variants (SR-A1, 1.1, 3, 4, 5, 6, etc.) have differential expression and ligand specificity, contributing to tissue diversity and function

Other names

SR-A1 (SCARA1, MSR1)SR-A1.1 (SR-AII)SR-A1.2 (SR-AIII)SR-A3 (SCARA3, MSRL1, APC7)SR-A4 (SCARA4, COLEC12, SRCL)SR-A5 (SCARA5, TESR)SR-A6 (SCARA2, MARCO)Macrophage scavenger receptor

Ligand internalization and clearance (modified LDL, apoptotic cells, pathogens) Modulation of inflammation through interactions with toll-like receptors (TLRs) Alteration of lipid metabolism in macrophages (foam cell formation)