Chemotactic range fitting
Chemotactic responses elicited by the ligand-receptor interactions are distinguished generally upon the optimal effective concentration(s) of the ligand. Nevertheless, correlation of the amplitude elicited and ratio of the responder cells compared to the total number are also characteristic features of the chemotactic signaling. Investigations of ligand families (e.g. amino acids or oligopeptides) proved that there is a fitting of ranges (amplitudes; number of responder cells) and chemotactic activities: chemoattractant moiety is accompanied with wide, while chemorepellent character narrow ranges.
Kohidai L, Lang O and Csaba G (2003). "Chemotactic-range-fitting of amino acids and its correlations to physicochemical parameters in Tetrahymena pyriformis - Evolutionary consequences". Cell Mol Biol. 49: OL487–95. PMID 14995080.