 Putative SLCs, also called atypical SLCs, are novel, plausible secondary active or facilitative transansporter proteins that share ancestral background with the known SLCs.However, they have not been assigned a name according to the SLC root system, or been classified into any of the existing SLC families.The atypical SLCs of MFS type can, however, be subdivided into 15 Putative MFS Transporter Families (AMTF).