Presence of an ecdysteroid-specific binding protein (“receptor”) in epithelial tissue culture cells of Chironomus tentans

• Published in: Journal of insect physiology Vol. 34; no. 8; pp. 797 - 803
• Main Authors: Turberg, A., Spindler-Barth, M., Lutz, B., Lezzi, M., Spindler, K.-D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 1988; Elsevier
• Subjects: Biochemistry. Physiology. Immunology; Biological and medical sciences; Chironomidae; Chironomus tentans; Chironomus tentans cell line; ecdysteroid “receptor”; ecdysteroids; Fundamental and applied biological sciences. Psychology; high affinity binding protein; Insecta; Invertebrates; Physiology. Development; Chironomus tentans cell line; high affinity binding protein; ecdysteroid “receptor”; ecdysteroids; Chironomidae; Cell culture; Chironomus tentans; Steroid hormone; Insecta; Binding site; Binding protein; Ecdysteroide; Arthropoda; Epithelial cell; Kinetics; Invertebrata; Diptera; Physicochemical properties
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/0022-1910(88)90154-0

In an epithelial cell line of Chironomus tentans, the presence of a high-affinity binding component for moulting hormones is demonstrated using whole cells or cell extracts. The K d-value for ponasterone A binding to whole cells is 0.17 × 10 −9 M, and to cell extracts it is 0.65 × 10 −9 M or 0.17 × 10 −9 M as determined by Scatchard or kinetic analyses, respectively. Competition assays revealed the relative affinities of this component to the three ecdysteroids ponasterone A, 20-hydroxyecdysone and ecdysone to be 1, 0.013 and 0.0029 Hydrocortisone, a steroid hormone from vertebrates, does not compete with ponasterone A for binding. Binding of ponasterone A is reduced by increasing salt concentrations. The apparent half-life of the binding component at 4°C is 41 h, and it is increased to 98 h when cell extracts are stored in the presence of ligand. The binding component is sensitive to proteinase and to agents blocking sulfhydryl groups.