Structural determinants within residues 180-199 of the rodent alpha 5 nicotinic acetylcholine receptor subunit involved in alpha-bungarotoxin binding

• Published in: Biochemistry (Easton) 1991-11, Vol.30 (44), p.10730-10738
• Main Authors: McLane, K E, Wu, X D, Conti-Tronconi, B M
• Format: Article
• Language: English
• Subjects: 550201 - Biochemistry- Tracer Techniques; ACETYLCHOLINE; alpha -bungarotoxin; AMINES; AMINO ACID SEQUENCE; AMINO ACIDS; AMMONIUM COMPOUNDS; Animals; ANTIGENS; AUTONOMIC NERVOUS SYSTEM AGENTS; BASIC BIOLOGICAL SCIENCES; BETA DECAY RADIOISOTOPES; Binding Sites; Binding, Competitive; Bungarotoxins - metabolism; CARBOXYLIC ACIDS; CYSTEINE; Cysteine - chemistry; DAYS LIVING RADIOISOTOPES; DRUGS; ELECTRON CAPTURE RADIOISOTOPES; ESTERS; HAZARDOUS MATERIALS; INTERMEDIATE MASS NUCLEI; INTERNAL CONVERSION RADIOISOTOPES; IODINE 125; IODINE ISOTOPES; ISOTOPE APPLICATIONS; ISOTOPES; Macromolecular Substances; MATERIALS; MEMBRANE PROTEINS; Molecular Sequence Data; MOLECULAR STRUCTURE; NEUROREGULATORS; nicotinic; NUCLEI; ODD-EVEN NUCLEI; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; Oxidation-Reduction; PARASYMPATHOMIMETICS; Peptide Fragments - chemistry; Peptide Fragments - metabolism; PROTEINS; QUATERNARY COMPOUNDS; RADIOISOTOPES; RADIORECEPTOR ASSAY; Rats; RECEPTORS; Receptors, Nicotinic - chemistry; Receptors, Nicotinic - metabolism; Sequence Homology, Nucleic Acid; Sulfhydryl Compounds; THIOLS; Torpedo; TOXIC MATERIALS; TOXINS; TRACER TECHNIQUES
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00108a018

Synthetic peptides corresponding to sequence segments of the nicotinic acetylcholine receptor (nAChR) alpha subunits have been used to identify regions that contribute to formation of the binding sites for cholinergic ligands. We have previously defined alpha-bungarotoxin (alpha-BTX) binding sequences between residues 180 and 199 of a putative rat neuronal nAChR alpha subunit, designated alpha 5 [McLane, K. E., Wu, X., & Conti-Tronconi, B. M. (1990) J. Biol. Chem. 265, 9816-9824], and between residues 181 and 200 of the chick neuronal alpha 7 and alpha 8 subunits [McLane, K. E., Wu, X., Schoepfer, R., Lindstrom, J., & Conti-Tronconi, B. M. (1991) J. Biol. Chem. (in press)]. These sequences are relatively divergent compared with the Torpedo and muscle nAChR alpha 1 alpha-BTX binding sites, which indicates a serious limitation of predicting functional domains of proteins based on homology in general. Given the highly divergent nature of the alpha 5 sequence, we were interested in determining the critical amino acid residues for alpha-BTX binding. In the present study, the effects of single amino acid substitutions of Gly or Ala for each residue of the rat alpha 5(180-199) sequence were tested, using a competition assay, in which peptides compete for 125I-alpha-BTX binding with native Torpedo nAChR.