Tachykinin-related peptide precursors in two cockroach species

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Abstract
Tachykinins and tachykinin-related peptides (TKRPs) play major roles in signaling in the nervous system and intestine of both invertebrates and vertebrates. Here we have identified cDNAs encoding precursors of multiple TKRPs from the cockroaches Leucophaea maderae and Periplaneta americana. All nine LemTKRPs that had been chemically isolated in earlier experiments could be identified on the precursor of L. maderae. Four previously unidentified LemTKRPs were found in addition on the precursor. The P. americana cDNA displayed an open reading frame very similar to that of L. maderae with 13 different TKRPs. MALDI-TOF mass spectra from tissues of both species confirms the presence of all the TKRPs encoded on the precursor plus two additional peptides that are cleavage products of the N-terminally extended TKRPs. A tissue-specific distribution of TKRPs was observed in earlier experiments at isolation from brain and midgut of L. maderae. Our data do not suggest a differential gene expression but a different efficacy in processing of LemTKRP-2 and Lem/PeaTKRP-3 in the brain and intestine, respectively. This results in a gut-specific accumulation of these extended peptides, whereas in the brain their cleavage products, LemTKRP-1 and LemTKRP-3(11-19), are most abundant. Mass spectrometric analysis demonstrated the occurrence of the different TKRPs in single glomeruli of the tritocerebrum and in cells of the optical lobe.