Abstract
Biosynthesis of the egg-laying hormone in the bag cell neurons of Aplysia californica was studied. Bag cells were incubated with leucine-3H in vitro for 30 min and rinsed for variable periods of time in a chase medium. The distribution of incorporated label among proteins within the cells was assayed by electrophoresis of an homogenate on sodium dodecyl sulfate polyacrylamide gels. Results from rinse times shorter than 30 min revealed that the predominant synthetic product is a 25,000 dalton protein. With longer rinse times, this species was reduced and two species of lower molecular weight became prominent. This redistribution of radioactivity was quantitative and was not prevented by inhibition of protein synthesis during the rinse. A 10°C reduction in temperature (from 15°C) blocked the redistribution. These data are interpreted to indicate that the 25,000 dalton molecule is a precursor which is cleaved enzymatically to yield two lower molecular weight products. One product is a 12,000 dalton molecule which remains in the cell bodies. The other is a molecule of <10,000 daltons which is exported from the somata into the neurohemal regions of the connective tissue. Perfusion of these regions with high [K+] medium results in the release of this product into the medium. It is concluded that this product is the 6000 dalton egg-laying hormone (ELH).
Full Text
The Full Text of this article is available as a PDF (882.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arch S. Polypeptide secretion from the isolated parietovisceral ganglion of Aplysia californica. J Gen Physiol. 1972 Jan;59(1):47–59. doi: 10.1085/jgp.59.1.47. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Coggeshall R. E. A cytologic analysis of the bag cell control of egg laying in Aplysia. J Morphol. 1970 Dec;132(4):461–485. doi: 10.1002/jmor.1051320407. [DOI] [PubMed] [Google Scholar]
- Coggeshall R. E. A light and electron microscope study of the abdominal ganglion of Aplysia californica. J Neurophysiol. 1967 Nov;30(6):1263–1287. doi: 10.1152/jn.1967.30.6.1263. [DOI] [PubMed] [Google Scholar]
- EAGLE H. Amino acid metabolism in mammalian cell cultures. Science. 1959 Aug 21;130(3373):432–437. doi: 10.1126/science.130.3373.432. [DOI] [PubMed] [Google Scholar]
- Fawcett C. P., Powell A. E., Sachs H. Biosynthesis and release of neurophysin. Endocrinology. 1968 Dec;83(6):1299–1310. doi: 10.1210/endo-83-6-1299. [DOI] [PubMed] [Google Scholar]
- Kupfermann I. Stimulation of egg laying by extracts of neuroendocrine cells (bag cells) of abdominal ganglion of Aplysia. J Neurophysiol. 1970 Nov;33(6):877–881. doi: 10.1152/jn.1970.33.6.877. [DOI] [PubMed] [Google Scholar]
- Kupfermann I. Stimulation of egg laying: possible neuroendocrine function of bag cells of abdominal ganglion of Aplysia californica. Nature. 1967 Nov 25;216(5117):814–815. doi: 10.1038/216814a0. [DOI] [PubMed] [Google Scholar]
- Schwartz J. H., Castellucci V. F., Kandel E. R. Functioning of identified neurons and synapses in abdominal ganglion of Aplysia in absence of protein synthesis. J Neurophysiol. 1971 Nov;34(6):939–953. doi: 10.1152/jn.1971.34.6.939. [DOI] [PubMed] [Google Scholar]
- Steiner D. F., Cho S., Oyer P. E., Terris S., Peterson J. D., Rubenstein A. H. Isolation and characterization of proinsulin C-peptide from bovine pancreas. J Biol Chem. 1971 Mar 10;246(5):1365–1374. [PubMed] [Google Scholar]
- Steiner D. F., Oyer P. E. The biosynthesis of insulin and a probable precursor of insulin by a human islet cell adenoma. Proc Natl Acad Sci U S A. 1967 Feb;57(2):473–480. doi: 10.1073/pnas.57.2.473. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ward S., Wilson D. L., Gilliam J. J. Methods for fractionation and scintillation counting of radioisotope-labeled polyacrylamide gels. Anal Biochem. 1970 Nov;38(1):90–97. doi: 10.1016/0003-2697(70)90158-2. [DOI] [PubMed] [Google Scholar]
- Wilson D. L. Molecular weight distribution of proteins synthesized in single, identified neurons of Aplysia. J Gen Physiol. 1971 Jan;57(1):26–40. doi: 10.1085/jgp.57.1.26. [DOI] [PMC free article] [PubMed] [Google Scholar]