Transportin-3Transportin-3 is a protein that in humans is encoded by the TNPO3 gene.FunctionTNPO3 is a nuclear import receptor for serine/arginine-rich proteins, including Serine/arginine-rich splicing factor 1, which are essential precursor-mRNA splicing factors.Clinical significanceThe TNPO3-IRF5 locus is implicated in primary biliary cirrhosis and systemic sclerosis.