R15 alpha 1 and R 15 alpha 2 peptides from Aplysia: comparison of bioactivity, distribution, and function of two peptides generated by alternative splicing.

Publication Type:

Journal Article


Journal of neurobiology, Volume 22, Issue 4, p.405-17 (1991)


Animals, Antibodies, Monoclonal, Aplysia, Ganglia, Immunohistochemistry, Methionine, Neuropeptides, Nucleic Acid Hybridization, RNA Splicing


The mRNA precursor encoded by the R15 gene is alternatively spliced in different neurons to form two related variants, R15-1 and R15-2 mRNA. One of the peptides encoded by the R15-2 mRNA, the R15 alpha 1 peptide, is expressed in the endogenously bursting neuron R15 and mediates some of its central and peripheral synaptic actions. In this study we found that the R15 alpha 2 peptide, which is encoded by the R15-1 mRNA, is synthesized in other neurons in the abdominal ganglion and is also bioactive. The R15 alpha 1 and R15 alpha 2 peptides were found to exert many similar actions on the cardiovascular, digestive, respiratory, and reproductive systems. However, the differences between many of the pharmacological effects of the R15 alpha 1 and R15 alpha 2 peptides indicate that alternative splicing in this system results in two functionally different peptides. Widespread immunoreactivity was found for an antibody directed against the R15 alpha 2 peptide, both in the central nervous system and the periphery. But because of the shared sequence with the R15 alpha 1 peptide, the antibody cross-reacts with the R15 alpha 1 peptide. To distinguish immunocytochemically between the two peptides, we also raised a second antibody that recognizes only the R15 alpha 1 peptide. This antibody labeled the cell body of only one neuron in the central nervous system, R15, although widespread immunoreactivity was found in axons and varicosities in the periphery.