Members of this family are transmembrane proteins. Several are Leishmania putative proteins that are thought to be pteridine transporters. One such protein Swiss:Q25272, previously termed (and is still annotated as) ORFG, was shown to encode a biopterin transport protein using null mutants, thus being subsequently renamed BT1. The significant similarity of ORFG/BT1 to Trypanosoma brucei ESAG10 (a putative transmembrane protein and another member of this family) was previously noted. This family also contains five putative Arabidopsis thaliana proteins of unknown function. In addition, it also contains two predicted prokaryotic proteins (from the cyanobacteria Synechocystis and Synechococcus).
Jiyao W et al.(2023). "The conserved domain database in 2023.",