The domain within your query sequence starts at position 953 and ends at position 1234; the E-value for the Met_synt_B12 domain shown below is 2.5e-114.



PFAM accession number:PF02965
Interpro abstract (IPR004223):

Vitamin B12 dependent methionine synthase EC (5-methyltetrahydrofolate--homocysteine S-methyltransferase) catalyses the conversion of 5-methyltetrahydrofolate and L-homocysteine to tetrahydrofolate and L-methionine as the final step in de novo methionine biosynthesis. The enzyme requires methylcobalamin as a cofactor. In humans, defects in this enzyme are the cause of autosomal recessive inherited methylcobalamin deficiency (CBLG), which causes mental retardation, macrocytic anemia and homocystinuria. Mild deficiencies in activity may result in mild hyperhomocysteinemia, and mutations in the enzyme may be involved in tumorigenesis. Vitamin B12 dependent methionine synthase is found in prokaryotes and eukaryotes, but in prokaryotes the cofactor is cobalamin.

In Escherichia coli, methionine synthase is a large enzyme composed of four structurally and functionally distinct modules: the first two modules bind homocysteine and tetrahydrofolate, the third module binds the B12 cofactor ( IPR003759 IPR006158 ), and the C-terminal module (activation domain) binds S-adenosylmethionine. The activation domain is essential for the reductive activation of the enzyme. During the catalytic cycle, the highly reactive cob(I)alamin intermediate can be oxidised to produce an inactive cob(II)alamin enzyme; the enzyme is then reactivated via reductive methylation by the activation domain [ (PUBMED:11731805) ]. The activation domain adopts an unusual alpha/beta fold.

GO process:methionine biosynthetic process (GO:0009086)
GO function:methionine synthase activity (GO:0008705)

This is a PFAM domain. For full annotation and more information, please see the PFAM entry Met_synt_B12