Regulates the dimerization of homeodomain protein HNF-1- alpha and enhances its transcriptional activity. Involved in tetrahydrobiopterin biosynthesis. Seems to both prevent the formation of 7-pterins and accelerate the formation of quinonoid-BH2 (By similarity).
Stadler, Rexhepaj, Singan, Murphy, Pepperkok, Uhlén, Simpson, Lundberg: "Immunofluorescence and fluorescent-protein tagging show high correlation for protein localization in mammalian cells." in: Nature methods, Vol. 10, Issue 4, pp. 315-23, (2013) (PubMed).