Gamma-butyrobetaine dioxygenase

Gamma-butyrobetaine dioxygenase (BBOX1) is a metabolic enzyme that catalyzes the formation of L-carnitine from gamma-butyrobetaine (UniProt: O75936). L-carnitine is essential for mitochondrial fatty acid β-oxidation and cellular energy metabolism. The enzyme is a 387-amino acid protein with a molecular mass of approximately 44.7 kDa.

BBOX1 is ubiquitously expressed across tissues and plays a central role in carnitine biosynthesis, linking amino acid metabolism to mitochondrial function. No baseline disease associations are documented in UniProt for this protein.

In Alzheimer's disease, BBOX1 is upregulated in post-mortem AD brain tissue compared to age-matched controls (mean log₂FC = 0.84; direction: up; Chaparral AD proteomics). This elevation was detected across 2 of 4 subcellular fractions in a TMT-labeled proteomic study of human post-mortem tissue, suggesting increased L-carnitine synthesis capacity in the AD brain. The functional significance of this upregulation in AD pathophysiology remains to be elucidated.