AlaE is a family of Gram-negative amino-acid transporters. It is not entirely clear why bacteria export metabolites but recent studies have shown that many excrete alanine. AlaE is likely to be the exporter protein for L-alanine. UniProtKB:A8ANM6, UniProt:G4R961 and UniProt:H5SVY7 are classified as putative alanine exporters [1].

1: Inducible L-alanine exporter encoded by the novel gene ygaW (alaE) in Escherichia coli. Hori H, Yoneyama H, Tobe R, Ando T, Isogai E, Katsumata R; Appl Environ Microbiol. 2011;77:4027-4034. PMID:21531828