In mammalian tissues the C-terminal amide structure has been found to occur only in neuroactive or hormonally-active peptides. About half known neuropeptide and peptide hormones have this unique chemical feature. Using a chemical detection method, a search for previously unknown peptides that possess the C-terminal amide structure in extracts of brain and intestine was carried out and a number of novel neuropeptides and hormonal peptides, designated neuropeptide Y, PHI, peptide YY, galanin and neuropeptide K were isolated. We recently performed a similar search in porcine pancreas and found a high concentration of a peptide having a glycine amide at its C-terminus. Here we report the isolation, primary structure and biological activity of this novel peptide. The 49-residue peptide strongly inhibits glucose-induced insulin release from the isolated perfused pancreas and was therefore named pancreastatin. It may be important in the regulation of insulin secretion and in the pathogenesis and treatment of diabetes mellitus.

Monoclonal antibodies were previously used to identify two glycoproteins, called fasciclin I and II (70 and 95 kDa, respectively), which are expressed on different subsets of axon fascicles in the grasshopper (Schistocerca americana) embryo. Here the monoclonal antibodies were used to purify these two membrane-associated glycoproteins for further characterization. Fasciclin II appears to be an integral membrane protein, whereas fasciclin I is an extrinsic membrane protein.The amino acid sequences of the amino terminus and fragments of both proteins were determined. Using synthetic oligonucleotide probes and antibody screening, we isolated genomic and cDNA clones. Partial DNA sequences of these clones indicate that they encode fasciclins I and II.Previous studies gave rise to the labeled pathways hypothesis, which predicts that axon fascicles in the embryonic neuropil are differentially labeled by surface recognition molecules used for growth cone guidance (e.g., see refs. 1-6). To identify candidates for axonal recognition molecules, monoclonal antibodies (mAbs) were generated that recognize surface antigens expressed on subsets of axon fascicles in both grasshopper (Schistocerca americana) (7) and Drosophila (8) embryos.These mAbs were used to characterize three different membrane-associated glycoproteins, called fasciclin I and II in the grasshopper and fasciclin III in Drosophila, which have several features in common. All three proteins (i) are expressed on different subsets of axon fascicles during development, (ii) are regionally expressed on particular portions of embryonic neurons where their axons fasciculate together, (iii) are dynamically expressed duiing axon outgrowth, and (iv) are expressed outside the developing nervous system at other times and places.

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