The function of Ensembl gene identifier ENSG00000166228 (PCBD1, pterin-4 alpha-carbinolamine dehydratase 1) is as follows. Involved in tetrahydrobiopterin biosynthesis (By similarity). Seems to both prevent the formation of 7-pterins and accelerate the formation of quinonoid-BH2. Coactivator for HNF1A-dependent transcription (By similarity). Regulates the dimerization of homeodomain protein HNF1A and enhances its transcriptional activity (By similarity). Also acts as a coactivator for HNF1B-dependent transcription (PubMed:24204001). {ECO:0000250|UniProtKB:P61459, ECO:0000269|PubMed:24204001}.