Activator of the beta-catenin signaling cascade, leading to TCF-dependent gene activation. Acts both in the canonical Wnt/beta-catenin-dependent pathway, possibly via a direct interaction with Wnt proteins, and in a Wnt-independent beta catenin pathway through a receptor signaling pathway that may not use frizzled/LRP receptors.
Involvement in disease
Defects in RSPO4 are the cause of anonychia congenita (ANONC) [MIM:206800]. A rare condition characterized by the absence or severe hypoplasia of all fingernails and toenails without significant bone anomalies.
Belongs to the R-spondin family. Contains 1 FU (furin-like) repeat. Contains 1 TSP type-1 domain.
The FU repeat is required for activation and stabilization of beta-catenin.
Tyr-112 may be phosphorylated; however as this position is probably extracellular, the vivo relevance is not proven.