This protein represents a small family of integral membrane proteins from Gram-negative bacteria, a Gram-positive bacteria, and an archaeal species. Members of this family contain 15 to 18 GES predicted transmembrane regions, and this family has extensive homology to a family of yeast tetrapeptide transporters, including isp4 (Schizosaccharomyces pombe) and Opt1 (Candida albicans). EspB, an apparent equivalog from Myxococcus xanthus, shares an operon with a two component system regulatory protein, and is required for the normal timing of sporulation after the aggregation of cells. This is consistent with a role in transporting oligopeptides as signals across the membrane. [Transport and binding proteins, Amino acids, peptides and amines]
Jiyao W et al.(2023). "The conserved domain database in 2023.",