Abstract
N-Formylation and N-methylation of the alpha-amino group of L- phenylalanine result in extremely decreased responses of the labellar sugar receptor of the fleshfly, whereas the same structural alteration of L-valine hardly affects the response. Methyl esterification of the alpha-carboxyl group of phenylalanine, on the other hand, maintains the response to some extent, but similar treatment of valine completely diminishes the response. The aromatic structure in phenylalanine is not essential for stimulation. These results suggest a substantial difference in the stereospecificities and functional group specificities of the furnase (F) and aliphatic carboxylate (T) sites in the sugar receptor. The effect of small peptides on the sugar receptor was examined systematically. Their effectiveness depends mainly on the place of the constituent amino acids rather than on their composition, indicating the decisive role that certain aliphatic amino acids in the C-terminal position play in stimulation. Remarkable regularities in the stimulating effectiveness of small peptides exactly correspond to the stereospecificity of each receptor site. We propose two hypothetical models of the F and T sites, which involve three and two subsites, respectively, that are capable of hydrogen bond formation. The F and T sites also have a hydrophobic subsite that discriminates the R groups of the stimulants and a few spatial barriers.
Full Text
The Full Text of this article is available as a PDF (976.2 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Dethier V. G., Hanson F. E. Electrophysiological responses of the chemoreceptors of the blowfly to sodium salts of fatty acids. Proc Natl Acad Sci U S A. 1968 Aug;60(4):1296–1303. doi: 10.1073/pnas.60.4.1296. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koshland D. E., Jr A response regulator model in a simple sensory system. Science. 1977 Jun 3;196(4294):1055–1063. doi: 10.1126/science.870969. [DOI] [PubMed] [Google Scholar]
- MORITA H., YAMASHITA S. Generator potential of insect chemoreceptor. Science. 1959 Oct 9;130(3380):922–922. doi: 10.1126/science.130.3380.922. [DOI] [PubMed] [Google Scholar]
- Mazur R. H., Schlatter J. M., Goldkamp A. H. Structure-taste relationships of some dipeptides. J Am Chem Soc. 1969 May 7;91(10):2684–2691. doi: 10.1021/ja01038a046. [DOI] [PubMed] [Google Scholar]
- Morita H. Primary processes of insect chemoreception. Adv Biophys. 1972;3:161–198. [PubMed] [Google Scholar]
- Shimada I. Chemical treatments of the labellar sugar receptor of the fleshfly. J Insect Physiol. 1975 Sep;21(9):1565–1574. doi: 10.1016/0022-1910(75)90193-6. [DOI] [PubMed] [Google Scholar]
- Shimada I., Shiraishi A., Kijima H., Morita H. Separation of two receptor sites in a single labellar sugar receptor of the flesh-fly by treatment with p-chloromercuribenzoate. J Insect Physiol. 1974 Mar;20(3):605–621. doi: 10.1016/0022-1910(74)90166-8. [DOI] [PubMed] [Google Scholar]
- Shimada I. The stimulating effect of fatty acids and amino acid derivatives on the labellar sugar receptor of the fleshfly. J Gen Physiol. 1978 Jan;71(1):19–36. doi: 10.1085/jgp.71.1.19. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shiraishi A., Kuwabara M. The effects of amino acids on the labellar hair chemosensory cells of the fly. J Gen Physiol. 1970 Dec;56(6):768–782. doi: 10.1085/jgp.56.6.768. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wilczek M. The distribution and neuroanatomy of the labellar sense organs of the blowfly Phormia regina Meigen. J Morphol. 1967 Jul;122(3):175–201. doi: 10.1002/jmor.1051220303. [DOI] [PubMed] [Google Scholar]