This model discriminates cysteine synthases (EC 2.5.1.47) (both CysK and CysM) from cystathionine beta-synthase, a protein found primarily in eukaryotes and carrying a C-terminal CBS domain lacking from this protein. Bacterial proteins lacking the CBS domain but otherwise showing resemblamnce to cystathionine beta-synthases and considerable phylogenetic distance from known cysteine synthases were excluded from the seed and score below the trusted cutoff. [Amino acid biosynthesis, Serine family]
Jiyao W et al.(2023). "The conserved domain database in 2023.",