Acts as a sulfur carrier required for molybdopterin biosynthesis. Component of the molybdopterin synthase complex that catalyzes the conversion of precursor Z into molybdopterin by mediating the incorporation of 2 sulfur atoms into precursor Z to generate a dithiolene group. In the complex, serves as sulfur donor by being thiocarboxylated (-COSH) at its C-terminus by MOCS3. After interaction with MOCS2B, the sulfur is then transferred to precursor Z to form molybdopterin.
Subcellular locations: Cytoplasm, Cytosol
Widely expressed. Highest levels are found in heart and skeletal muscle. Lower levels are present in brain, kidney and pancreas. Very low levels are found in lung and peripheral blood leukocytes.