Molybdopterin synthase catalytic subunit (MOCS2)

Molybdopterin synthase catalytic subunit (MOCS2) is an enzyme essential for the final step in the synthesis of the molybdenum cofactor (MoCo), a crucial prosthetic group for all eukaryotic molybdoenzymes[1][3][5]. MOCS2 encodes two proteins via alternative splicing and overlapping reading frames—MOCS2A (small subunit, sulfur carrier) and MOCS2B (large/catalytic subunit)[1][3]. The functional holoenzyme is a complex of these two subunits, catalyzing the conversion of precursor Z into molybdopterin with the incorporation of two sulfur atoms, which are necessary for MoCo's dithiolene group[3][5][6]. The MoCo biosynthetic pathway is vital for functional enzymes such as xanthine dehydrogenase, and defects in MOCS2 cause molybdenum cofactor deficiency type B—a severe, early-lethal, neurodegenerative metabolic disorder characterized biochemically by undetectable serum uric acid, high urinary xanthine, and sometimes increased sulfite levels[1][2][3][4]. Recent studies link MOCS2 with broader metabolic processes, including nucleotide metabolism, mRNA methylation, and polyamine synthesis—highlighting its importance far beyond classical enzyme cofactor biosynthesis[4]. No direct therapeutic drugs targeting MOCS2 exist, but mutations are critical biomarkers for MoCo deficiency diagnosis and prognosis[2][3].

Other names

Molybdenum cofactor synthesis 2Molybdenum cofactor synthesis protein 2AMolybdenum cofactor synthesis protein 2BMolybdopterin synthase sulfur carrier subunitMOCS2AMOCS2BMOCO1MOCO1-AMOCO1-BMolybdenum cofactor synthesis protein 2 small subunitMolybdenum cofactor synthesis protein 2 large subunitMolybdopterin-synthase large subunitMolybdopterin-synthase small subunitSulfur carrier protein MOCS2AMolybdopterin synthase catalytic subunitMolybdenum cofactor biosynthesis protein EMCBPEMPTS