| Modification Notes |
Roof plate-specific Spondins (R-Spondins) are secreted proteins that possess a Furin-like cysteine-rich domain and are involved in regulating ∫-catenin function. R-Spondin4, also known as RSPO4, is a 234 amino acid secreted protein that, characteristic of R-Spondins, contains one Furin-like repeat and one TSP type-1 domain. R-Spondin4 interacts with heparin and is able to activate the ∫-catenin signaling cascade, possibly via control of the Wnt/∫-catenin signaling pathway. Defects in the gene encoding R-Spondin4 are the cause of anonychia, an autosomal recessive condition characterized by severe hypoplasia (underdevelopment) of fingernails and toenails. R-Spondin4 exists as multiple alternatively spliced isoforms that are encoded by a gene which maps to human chromosome 20. |