Plays a role in chemotaxis signal transduction system in order to colonize the host stomach. May act as a phosphate sink to control the flow of phosphate to CheAY. Phosphorylated; probably by transfer of CheAY phosphate group. Deletion mutant is fully chemotactic and forms swarms the same way as wild-type strain (PubMed:11535789). Mutant shows however defects in mouse colonization (PubMed:19332820).