Characterization of a diuretic hormone receptor from the tobacco hornworm,Manduca sexta |
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Authors: | Jeff D. Regan Jorge P. Li Robert L. Carney Steven J. Kramer |
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Abstract: | We have characterized a diuretic hormone receptor from the tobacco hornworm, Manduca sexta. A single high affinity binding site for the 41 amino acid M. sexta diuretic hormone was found in membranes prepared from Malpighian tubules of fifth stadium larvae. The site has a Kd = 79 pM and Bmax = 3.1 pmol/mg protein. The dissociation rate constant was determined to be 0.11 min?1 with a corresponding half-life of 6.4 min. Receptor binding of the hormone is inhibited by Ca2+ and Mg2+, while Na+ and K+ inhibit binding to a lesser extent. Truncated diuretic hormone analogs in which up to 20 amino acids were removed from the N-terminus maintain high affinity for the receptor. A diuretic hormone from Locusta migratoria which has 43% sequence identity with the M. sexta diuretic hormone also possesses a high affinity for the receptor. Conformational analysis of the M. sexta diuretic hormone indicates the core region of the peptide assumes a helical conformation, which may have implications in the binding of the peptide to the receptor. © 1993 Wiley-Liss. Inc. |
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Keywords: | neuropeptide Malpighian tubule Locusta migratoria |
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