PCBD1

PCBD1 (pterin-4 alpha-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor 1 alpha) is a protein that in humans is encoded by the PCBD1 gene. This protein plays a crucial role in the metabolism of phenylalanine and is involved in the biochemical pathways of tetrahydrobiopterin (BH4) synthesis and regeneration. BH4 is essential for the hydroxylation reactions that metabolize several amino acids, including phenylalanine, and is also involved in the production of neurotransmitters.

Function

PCBD1 acts as a dimerization cofactor for hepatocyte nuclear factor 1 alpha (HNF1A), a transcription factor involved in glucose and lipid metabolism. Besides its role in metabolism, PCBD1 is implicated in the enzymatic process that regenerates tetrahydrobiopterin (BH4), an essential cofactor for phenylalanine, tyrosine, and tryptophan hydroxylases. These enzymes are critical for the synthesis of several key neurotransmitters and for the degradation of phenylalanine. Deficiencies in BH4 can lead to various metabolic disorders, including phenylketonuria (PKU).

Clinical Significance

Mutations in the PCBD1 gene can lead to a rare disorder known as Hyperphenylalaninemia, specifically the BH4-deficient Hyperphenylalaninemia D (HPA-D). This condition is characterized by elevated levels of phenylalanine in the blood, which, if untreated, can result in intellectual disability and other neurological issues. Early detection and treatment, such as dietary restrictions of phenylalanine and BH4 supplementation, can help prevent the severe outcomes associated with this disorder.

Genetic

The PCBD1 gene is located on chromosome 10 in humans. Variants within this gene have been studied for their association with metabolic diseases and their potential role in regulating metabolic pathways through interaction with HNF1A.

See Also

• Phenylketonuria
• Metabolism
• Hepatocyte nuclear factor 1 alpha
• Tetrahydrobiopterin deficiency

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