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Published April 1, 1980 | public
Journal Article Open

Purification and Primary Structure of Two Neuroactive Peptides That Cause Bag Cell Afterdischarge and Egg-Laying in Aplysia


Two neuroactive peptides, A and B, have been isolated from the atrial gland in the reproductive tract of Aplysia. Each of the two peptides is able to induced egg-laying behavior in recipient animals. In vitro recordings from the abdominal ganglion show that both peptides also trigger longlasting discharges in the bag cell neurons at concentrations around 0.1 µ M. The peptides were purified by a combination of ammonium sulfate precipitation, agarose gel filtration, and cation exchange chromatography. Each peptide has 34 amino acid residues. Microsequencing together with carboxypeptidase Y degradation and analysis of tryptic peptides revealed the following sequence for peptide A: H-Ala-Val-Lys-Leu-Ser-Ser-Asp-Gly-Asn-Tyr-Pro-Phe-Asp-Ley-Ser-Lys-Glu-Asp-Gly -Ala-Gln-Pro-Tyr-Phe-Met-Thr-Pro-Arg-Leu-Arg-Phe-Tyr-Pro-Ile. Peptide B differs from A in only four positions. The first nine residues of B are: Ala-Val-Lys-Ser-Ser-Ser-Tyr-Glu-Lys-, whereas residues 10-34 of B are identical to those of A. The calculated Mr of A is 3924 and that of B is 4032. The pI of peptide A as determined by isoelectric focusing in polyacrylamide gels is 7.9-8.1 and that of peptide B is 9.0-9.2. It is estimated that each atrial gland contains at least 150 µ g of peptide A and 50 µ g of B. Neither peptide resembles the egg-laying hormone isolated from bag cell neurons. It is postulated that the atrial gland peptides are released during copulation, and then by interacting with neuronal receptors in the head ganglia and pleuroabdominal connectives they cause the bag cells to afterdischarge, thereby releasing egg-laying hormone.

Additional Information

Copyright © 1980 by the National Academy of Sciences Communicated by Ray D. Owen, January 24, 1980 We thank Dr. W. A. Schroeder and Mrs. J. Shelton for carrying out the HPLC separation of tryptic peptides, Mr. J. Racs and Mr. V. Farnsworth for help in amino acid analysis, and Mr. D. Viele and Ms. A. Yuen for collecting A. californica. This work was supported by National Institutes of Health Grants NS15183 and NS13896 to F.S. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.


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