Recombinant Human FLRT2 Protein, CF

FLRT2 is one of three FLRT (fibronectin, leucine rich repeat, transmembrane) glycoproteins expressed in distinct areas of the developing brain and other tissues (1, 2). The 85 kDa type I transmembrane (TM) human FLRT2 is synthesized as a 660 amino acid (aa) precursor with a 35 aa signal sequence, a 506 aa extracellular domain (ECD), a 21 aa TM segment and a 98 aa cytoplasmic region. The ECD contains 10 N-terminal leucine-rich repeats flanked by cysteine-rich areas, and a juxtamembrane fibronectin type III domain (1). The human FLRT2 ECD shares 97%, 96%, 99%, 96% and 95% aa sequence identity with mouse, rat, equine, canine and bovine FLRT2 ECD, respectively. Human FLRT1 and FLRT3 ECDs share approximately 47% aa identity with FLRT2. The fibronectin domain of all three FLRTs can bind to FGF receptors (2). This binding is thought to regulate FGF signaling during development (2, 3). The LRR domains are responsible for both the localization of FLRTs in areas of cell contact and homotypic cell-cell association (4). This may be through direct interactions with other FLRT molecules or, as has been shown for FLRT3, by regulating internalization of adhesion molecules such as cadherins (4, 5). In adulthood, FLRT2 mRNA is most abundant in pancreas, but is also present in skeletal muscle, brain and heart (1). FLRT2 in mouse embryos shows highest expression in a subset of the sclerotome in the brain, the stomach, and posterior to the developing heart (2). This expression is distinct from that of FLRT1 and FLRT3 (2).