cDNA cloning of the sodium-influx-stimulating peptide in the mollusc, Lymnaea stagnalis

Abstract

We isolated and characterized a cDNA clone, encoding the prohormone of the sodium-influx-stimulating (SIS) peptide of the freshwater snail Lymnaea stagnalis. The prohormone is cleaved to generate a signal peptide of 23 amino acids and a SIS peptide of 77 amino acids. The SIS peptide as encoded by the cDNA represents a novel and complex neuropeptide, which controls the activity of sodium pumps in the integument, pericardium, ureter and nephridial gland. In situ hybridization showed that the SIS-peptide gene is expressed by the neuroendocrine, so-called Yellow Cells of the central nervous system.