Paralogous chemoreceptors mediate chemotaxis towards protein amino acids and the non-protein amino acid gamma-aminobutyrate (GABA).
Rico-Jiménez M, Muñoz-Martínez F, García-Fontana C, Fernandez M, Morel B, Ortega A, Ramos JL, Krell T. Mol Microbiol. 2013 Jun; 88(6):1230-43. Epub 2013 May 22.