Members of this protein family closely resemble ThiC, an enzyme that performs a complex rearrangement during thiamin biosynthesis, but instead occur as one of two adjacent additional paralogs to bona fide ThiC, in a conserved gene neighborhood with a pair of B12 binding domain/radical SAM domain proteins. Members of the ThiC family are non-canonical radical SAM enzymes, using a C-terminal Cys-rich motif to ligand a 4Fe-4S cluster that cleaves S-adenosylmethionine (SAM), but that sequence region does not belong to pfam04055.
Jiyao W et al.(2023). "The conserved domain database in 2023.",