Human R-Spondin 1

R-Spondin 1 is a 27 kDa secreted protein sharing ~40% amino acid (aa) identity with three other R-Spondin family members and regulating Wnt/ beta-Catenin signaling. It competes with the Wnt antagonist DKK-1 for binding to the Wnt co-receptors, Kremen and LRP-6, reducing their DKK-1-mediated internalization. R-Spondin 1 is expressed in early development at the roof plate boundary and is thought to contribute to dorsal neural tube development; postnatally, it is expressed by neuroendocrine cells in the intestine, adrenal gland and pancreas, and by epithelia in kidney and prostate (1-5).