The OPT family of oligopeptide transporters is distinct from the ABC Pfam:PF00005 and PTR Pfam:PF00854 transporter families. OPT transporters were first recognised in fungi (Candida albicans and Schizosaccharomyces pombe), but this alignment also includes orthologues from Arabidopsis thaliana. OPT transporters are thought to have 12-14 transmembrane domains and contain the following motif: SPYxEVRxxVxxxDDP [1].

1: Schizosaccharomyces pombe isp4 encodes a transporter representing a novel family of oligopeptide transporters. Lubkowitz MA, Barnes D, Breslav M, Burchfield A, Naider F, Becker JM; Mol Microbiol 1998;28:729-741. PMID:9643541