RNF43

Ring finger protein 43 is a protein that in humans is encoded by the RNF43 gene.

Function
The protein encoded by this gene is a RING-type E3 ubiquitin ligase and is predicted to contain a transmembrane domain, a protease-associated domain, an ectodomain, and a cytoplasmic RING domain. This protein is thought to negatively regulate Wnt signaling, and expression of this gene results in an increase in ubiquitination of frizzled receptors, an alteration in their subcellular distribution, resulting in reduced surface levels of these receptors. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Mar 2015]. A nuclear function for the protein has also been proposed but recently it was shown that this is an artifact, nuclear staining being an artifact of the antibodies employed. Cancer-associated RNF43 mutations lead to activation of β-catenin signaling through aberrantly increasing Wnt-receptor levels at the membrane. Importantly, inactivating N-terminal RNF43 mutations render cancer cells sensitive to Wnt antagonists, but mutations elsewhere do not.