MOCS2

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

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

Gene
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.

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

Genetic disease
Defects in both copies of MOCS2 cause the is_associated_with::molybdenum cofactor deficiency disease in babies.

Protein Structure
MOCS2A and MOCS2B subunits form dimers in solution. These dimers in turn dimerize to form the tetrameric molybdopterin synthase complex.