Human Stabilin-2 Alexa Fluor™ Plus 647-conjugated Antibody

Stabilin-2, also known as HARE (hyaluronan receptor for endocytosis) and FEEL-2 (fasciclin, EGF-like, laminin type EGF-like, and link domain containing scavenger receptor 2), is a type I transmembrane multi-domain protein that is the closest homolog of stabilin-1 (1, 2). It is a scavenger receptor that is expressed on sinusoidal endothelial cells of liver, spleen, and lymph node (1, 2). Its 2439 amino acid (aa) extracellular domain contains seven fasciclin domains, multiple EGF-like and laminin type EGF-like domains, and a link domain related to molecules of the TSG-6 superfamily (3). The 72 aa cytoplasmic tail of Stabilin-2 contains a motif that allows the AP2 classical cargo adaptor to direct cargo into clathrin-coated pits (4). As a recycling receptor, Stabilin-2 cycles from the membrane to clathrin-coated pits each 10‑15 minutes, with about two thirds of the protein found within the endocytic system at any one time (4). The link domain binds and mediates the systemic clearance of hyaluronan (HA) (2‑6). Within the link domain (aa 2198‑2295), human Stabilin-2 shares 86% and 89% aa identity with mouse and rat Stabilin-2, respectively. Total human HA is about 15 grams, of which about 5 grams are cleared each day (5). Stabilin-2 also mediates the endocytosis of chondroitin and chondroitin sulfate, advanced glycosylation end-product (AGE), collagen N-terminal propeptides and acetylated LDL (4‑7). Human Stabilin-2 mRNA encodes a 2251 aa, 315 kDa protein that produces an isoform of 190 kDa through proteolytic cleavage (2, 6). The 190 kDa form lacks some N-terminal fasciclin and EGF-like domains, but shows similar activities when compared with the 315 kDa form (2, 6).