Structure/activity relationships in the L-alanine taste receptor system of the channel catfish, Ictalurus punctatus.
In order to understand the molecular determinants of amino acid taste receptor binding and activation, structure/activity studies were performed using analogs of L-alanine in a competitive ligand binding assay and a taste neurophysiological preparation. The presence of both the amine and carboxylic acid in a charged and unhindered form is a primary requisite for a ligand to both bind and activate L-alanine receptors. Although a number of carboxylic acid derivatives are moderately good stimuli, their neural activity derives from action at receptors different from L-alanine receptors. Of the molecular parameters examined, chirality and molecular volume of the side chain are the most important factors in determining the binding and stimulatory efficacy of L-amino acid taste stimuli. Electronegativity of the side chain did not correlate with receptor site binding. Heterologous ligand-induced enhancement of the binding of L-[3H]alanine by a purified taste membrane preparation is described. Neurophysiological experiments support the hypothesis that this phenomenon may be a basis of peripheral sensory interactions.
Bryant
B P
BP
Monell Chemical Senses Center, Philadelphia, PA 19104.
Leftheris
K
K
D000409:Alanine / Q000031:analogs & derivatives / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive / Q000502:physiology; D007059:Ictaluridae / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000502:physiology*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000502:physiology*; D013652:Taste Threshold / Q000502:physiology
D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D000409:Alanine