R-Spondin 3 (RSPO3)

RSPO3 encodes a member of the thrombospondin type 1 repeat supergene family. In addition, the protein contains a furin-like cysteine-rich region. Furin-like repeat domains have been found in a variety of eukaryotic proteins involved in the mechanism of signal transduction by receptor tyrosine kinases.The 272-amino acid protein has an N-terminal cys-rich domain (CRD) and a central thrombospondin type-1 (THBS1) repeat (TSR) domain. Northern blot analysis detected 3.0- and 4.0-kb transcripts in placenta, lung, and skeletal muscle. RT-PCR revealed ubiquitous expression, with highest levels in placenta, small intestine, fetal thymus, and lymph node. RSPO3 expression was detected in all tumor tissues examined except a lung carcinoma and an ovarian carcinoma.