Original assignment of this protein family as cysteinyl-tRNA synthetase is controversial, supported by but challenged by and by subsequent discovery of the actual mechanism for synthesizing Cys-tRNA in species where a direct Cys--tRNA ligase was not found. Lingering legacy annotations of members of this family probably should be removed. Evidence against the role includes a signal peptide. This family as been renamed "extracellular protein" to facilitate correction. Members of this family occur in Deinococcus radiodurans (bacterial) and Methanococcus jannaschii (archaeal). A number of homologous but more distantly related proteins are annotated as alpha-1,4 polygalactosaminidases. The function remains unknown. [Unknown function, General]
Jiyao W et al.(2023). "The conserved domain database in 2023.",