Identification of multiple urechistachykinin peptides, gene expression, pharmacological activity, and detection using mass spectrometric analyses

Ulechistachykinin I and II (Uru-TK I and II) are invertebrate tachykinin-re lated peptides (TRPs), which have been isolated from echiuroid worms. The c DNA sequence encoding the Uru-TK I and II revealed that the precursor also encoded five TRP-like peptides. Here, we report the characterization of the se Uru-TK-like peptides named as Uru-TK III-VII. Northern and Southern blot analyses demonstrated that Uru-TK mRNA is localized in nerve tissue. In ad dition, the presence of the Uru-TK-like peptides as matured forms in the ne rve tissue was detected by mass spectrometric analysis, and identified thes e peptides were shown to exhibit a contractile activity on cockroach hindgu t that was as potent as that of Uru-TK II. Furthermore, synthetic Uru-TK-li ke peptide analogs which contained Met-NH, instead of Arg-NH, at their C-te rmini were shown to possess a potential to bind to a mammalian tachykinin r eceptor, indicating that Uru-TK-like peptides are likely to correspond to v ertebrate tachykinins, except for the difference at the C-terminal residue. These findings show that Uru-TK-like peptides are essentially equivalent t o Uru-TK I and II, leading to the proposal that Uru-TK-like peptides play a n essential role as invertebrate tachykinin neuropeptides. (C) 2000 Elsevie r Science Inc. All rights reserved.