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Molybdenum cofactor synthesis 2
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM603708 MGI1336894 HomoloGene32193 GeneCards: MOCS2 Gene
EC number
RNA expression pattern
PBB GE MOCS2 218212 s at tn.png
More reference expression data
Species Human Mouse
Entrez 4338 17434
Ensembl ENSG00000164172 ENSMUSG00000015536
UniProt O96007 Q9Z223
RefSeq (mRNA) NM_004531 NM_001113374
RefSeq (protein) NP_004522 NP_001106845
Location (UCSC) Chr 5:
53.1 – 53.11 Mb
Chr 13:
114.82 – 114.83 Mb
PubMed search [1] [2]

Molybdenum cofactor synthesis protein 2A and molybdenum cofactor synthesis protein 2B are a pair of proteins that in humans are encoded from the same MOCS2 gene.[1][2][3] These two proteins dimerize to form molybdopterin synthase.


Eukaryotic molybdoenzymes use a unique molybdenum cofactor (MoCo) consisting of a pterin, termed molybdopterin, and the catalytically active metal molybdenum. MoCo is synthesized from precursor Z (now known as cyclic pyranopterin monophosphate) by the heterodimeric enzyme molybdopterin synthase.[3]


The large and small subunits of molybdopterin synthase are both encoded from the MOCS2 gene by overlapping open reading frames. The proteins were initially thought to be encoded from a bicistronic transcript. They are now thought to be encoded from monocistronic transcripts. Alternatively spliced transcripts have been found for this locus that encode the large and small subunits.[3]

The MOCS2 gene contains 7 exons. Exons 1 to 3 encode MOCS2A (the small subunit), and exons 3 to 7 encode MOCS2B (large subunit).[1]

Genetic disease[edit]

Defects in both copies of MOCS2 cause the molybdenum cofactor deficiency disease in babies.[4]

Protein Structure[edit]

MOCS2A and MOCS2B subunits form dimers in solution. These dimers in turn dimerize to form the tetrameric molybdopterin synthase complex.[5]


  1. ^ a b Reiss J, Dorche C, Stallmeyer B, Mendel RR, Cohen N, Zabot MT (March 1999). "Human molybdopterin synthase gene: genomic structure and mutations in molybdenum cofactor deficiency type B". American Journal of Human Genetics 64 (3): 706–11. doi:10.1086/302296. PMC 1377787. PMID 10053004. 
  2. ^ Sloan J, Kinghorn JR, Unkles SE (February 1999). "The two subunits of human molybdopterin synthase: evidence for a bicistronic messenger RNA with overlapping reading frames". Nucleic Acids Research 27 (3): 854–8. doi:10.1093/nar/27.3.854. PMC 148257. PMID 9889283. 
  3. ^ a b c EntrezGene 4338: MOCS2 molybdenum cofactor synthesis 2
  4. ^ Ichida K, Aydin HI, Hosoyamada M et al. (2006). "A Turkish case with molybdenum cofactor deficiency". Nucleosides, Nucleotides & Nucleic Acids 25 (9–11): 1087–91. doi:10.1080/15257770600894022. PMID 17065069. 
  5. ^ Leimkuhler S, Freuer A, Araujo JA, Rajagopalan KV, Mendel RR (July 2003). "Mechanistic studies of human molybdopterin synthase reaction and characterization of mutants identified in group B patients of molybdenum cofactor deficiency". The Journal of Biological Chemistry 278 (28): 26127–34. doi:10.1074/jbc.M303092200. PMID 12732628. 

Further reading[edit]