RSPO-2, Recombinant, Human (R-Spondin 2, Cysteine-rich and Single Thrombospondin Domain Containing P

Human Roof plate-specific Spondin 2 isoform 1 (R-Spondin 2, RSPO-2), also known as cysteine-rich and single thrombospondin domain containing protein 2 (Cristin 2), is a 33kD secreted protein that belongs to the R-Spondin family. The four known human R-Spondins regulate Beta-catenin signaling and overlap in expression and function (1-3). Like other R-Spondins, R-Spondin 2 contains two adjacent cysteine-rich furin-like domains (aa 90-134) followed by a thrombospondin (TSP-1) motif (aa 144-204) and a C-terminal region rich in basic residues (aa 207-243). The basic region appears to mediate cell surface retention but not to influence function (1). R-Spondin 2 contains one potential N-glycosylation site. Of the three reported splice isoforms of human R-Spondin 2, isoform 2 lacks residues 1-67 of isoform 1, while isoform 3 has a glycine substitution for residues 32-95 of isoform 1. Human R-Spondin 2 is expressed in organs of endodermal origin in adults, including intestine and lung, and is downregulated in tumors of these tissues (1). In the embryonic mouse, R-Spondin 2 is expressed most highly in the hippocampus and in developing teeth and bones (4). Studies in Xenopus and mouse embryos indicate that R-Spondin 2 is an extracellular activator of Wnt/Beta-catenin signaling and is required for myogenesis (1). Mouse R-Spondin proteins bind both LRP-6 and Frizzled-8 but do not appear to form a ternary complex. (3) R-Spondin 2 overexpression in Xenopus also blocks signaling of TGF-Beta ligands activin, nodal and BMP-4 (1). Human R-Spondin 2 is highly conserved across species, sharing 97-98% aa identity with mouse, rat, dog, cow and opossum R-Spondin 2 and 86% aa identity with Xenopus R-Spondin 2 within aa 22-205. Mature R-Spondin 2 shares ~40% aa identity with R-Spondin 1, R-Spondin 3 and R-Spondin 4. Source: A DNA sequence encoding human R-Spondin 2 (Met 1-Gly 205, Accession # NP_848660) was fused to a six-histidine tag at the carboxy terminus. The chimeric protein was expressed in a mouse myeloma cell line, NS0. , Definition: Measured by its ability to synergize rmWnt-3A induced activation of Beta-catenin response in Topflash Luciferase assay (HEK293T cells). The typical ED50 is 3-12 ng/mL in the presence of 200 ng/mL rmWnt-3a. Applications: Suitable for use in ELISA and Western Blot. Other applications not tested. Recommended Dilution: ELISA:with an apparent KD<150 nM. , Western Blot: 22.0kD migrates as an ~ 25-29kD protein in SDS-PAGE under reducing conditions. , Optimal dilutions to be determined by the researcher. Storage and Stability: Lyophilized powder may be stored at 4°C for short-term only. Reconstitute to nominal volume by adding sterile PBS and store at -20°C. Reconstituted product is stable for 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.