Biochemical studies of taste sensation--VIII. Partial characterization of alanine-binding taste receptor sites of catfish Ictalurus punctatus using mercurials, sulfhydryl reagents, trypsin and phospholipase C.
1. Taste receptors for L-alanine in the channel catfish Ictalurus punctatus have been partially characterized. The binding activity, which is localized to a sedimentable fraction (Fraction P2), was assayed with L-[3H]alanine as the ligand. 2. Addition of HgCl2 or p-mercuribenzoate to the assay at 0.1-1 mM markedly inhibited binding. The effect was not reversible and was unaffected by increased L-alanine in the binding assay. 3. The sulfhydryl reagents iodoacetate, 5,5'-dithiobis(2-nitrobenzoic acid), arsenite, and N-ethylmaleimide did not show appreciable inhibition of binding. The results suggest that the inhibitory effect of mercurials is not on specific sulfhydryl groups at alanine-binding sites. 4. Treatment of Fraction P2 with phospholipase C decreased binding activity and treatment with trypsin led to increased binding activity.
D000409:Alanine / Q000378:metabolism*; D000818:Animals; D002397:Catfishes / Q000378:metabolism*; D007059:Ictaluridae / Q000378:metabolism*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008627:Mercuric Chloride; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000378:metabolism*; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013439:Sulfhydryl Reagents; D013649:Taste / Q000502:physiology*; D014357:Trypsin; D010738:Type C Phospholipases
D007202:Indicators and Reagents; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D013439:Sulfhydryl Reagents; D008627:Mercuric Chloride; D010738:Type C Phospholipases; D014357:Trypsin; D000409:Alanine