Part of a nutrient-sensing regulatory network composed of the two-component regulatory systems BtsS/BtsR and YpdA/YpdB, and their respective target proteins, BtsT and YhjX. Interacts with BtsS and YpdA. Induced by the two-component regulatory system YpdA/YpdB in response to pyruvate (PubMed:23222720). Regulated at post-transcriptional level by CsrA (PubMed:24659770). Belongs to the major facilitator superfamily.