Background:

R-Spondin1 (Rspo-1) belongs to the (Rspo) family of Wnt modulators. Currently, the family consists of four structurally related secreted ligands (Rspo 1-4), all containing the furin-like and thrombospondin structural domains. Postnatally, R-Spondin1 is expressed by neuroendocrine cells in the intestine, adrenal gland and pancreas, and by epithelia in kidney and prostate. R-Spondin1 regulates Wnt/β-catenin by competing with the Wnt antagonist DKK-1 for binding to the Wnt coreceptors, Kremen and LRP-6, reducing their DKK-1-mediated internalization. Recombinant Human R-Spondin1 is a 27.3 kDa protein consisting of 233 amino acid residues. Due to glycosylation, RSpondin1 migrates at an apparent molecular weight of approximately 41.0 kDa by SDS-PAGE analysis under reducing conditions.