Members of this protein family are radical SAM/SPASM domain proteins (see pfam04055 and TIGR04085) related to anaeroboic sulfatase maturating enzymes and the peptide modification enzyme PqqE. Members are found primarily in Cyanobacteria adjacent to a short protein, ~150 residues, in which the last ~60 residues tends to be repetitive and highly glycine-rich (see TIGR04260). The arrangement suggests modifications to the repetitive C-terminal region by this radical SAM domain enzyme, but the purpose of this system on the whole is unknown.
Jiyao W et al.(2023). "The conserved domain database in 2023.",