Santama N, Li K W, Bright K E, Yeoman M, Geraerts W P, Benjamin P R, Burke J F
Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Brighton, UK.
Eur J Neurosci. 1993 Aug 1;5(8):1003-16. doi: 10.1111/j.1460-9568.1993.tb00952.x.
In the pulmonate snail Lymnaea stagnalis, FMRFamide-like neuropeptides are encoded by a multi-exon genomic locus which is subject to regulation at the level of mRNA splicing. We aim to understand the post-translational processing of one resulting protein precursor encoding the tetrapeptide FMRFamide and a number of other putative peptides, and determine the distribution of the final peptide products in the central nervous system (CNS) and periphery of Lymnaea. We focused on two previously unknown peptide sequences predicted by molecular cloning to be encoded in the tetrapeptide protein precursor consecutively, separated by the tetrabasic cleavage site RKRR. Here we report the isolation and structural characterization of a novel non-FMRFamide-like peptide, the 22 amino acid peptide SEQPDVDDYLRDVVLQSEEPLY. The novel peptide is colocalized with FMRFamide in the CNS in a number of identified neuronal systems and their peripheral motor targets, as determined by in situ hybridization and immunocytochemistry. Its detection in heart excitatory motoneurons and in nerve fibres of the heart indicated that the novel peptide may play a role, together with FMRFamide, in heart regulation in the snail. The second predicted peptide, STEAGGQSEEMTHRTA (16 amino acids), was at very low abundance in the CNS and was only occasionally detected. Our current findings, suggestive of a distinct pattern of post-translational processing, allowed the reassessment of a previously proposed hypothesis that the two equivalent sequences in the Aplysia FMRFamide gene constitute a molluscan homologue of vertebrate corticotrophin releasing factor-like peptides.
在肺螺亚纲蜗牛椎实螺（Lymnaea stagnalis）中，类FMRF酰胺神经肽由一个多外显子基因组位点编码，该位点在mRNA剪接水平受到调控。我们旨在了解一种编码四肽FMRF酰胺和许多其他假定肽的蛋白质前体的翻译后加工过程，并确定最终肽产物在椎实螺中枢神经系统（CNS）和外周的分布。我们聚焦于通过分子克隆预测在四肽蛋白质前体中连续编码的两个先前未知的肽序列，它们被四碱基切割位点RKRR隔开。在此，我们报告一种新型非类FMRF酰胺肽（22个氨基酸的肽SEQPDVDDYLRDVVLQSEEPLY）的分离和结构表征。通过原位杂交和免疫细胞化学确定，这种新型肽在中枢神经系统的许多已鉴定神经元系统及其外周运动靶点中与FMRF酰胺共定位。在心脏兴奋性运动神经元和心脏神经纤维中检测到该肽，表明这种新型肽可能与FMRF酰胺一起在蜗牛的心脏调节中发挥作用。第二个预测肽STEAGGQSEEMTHRTA（16个氨基酸）在中枢神经系统中的丰度非常低，仅偶尔被检测到。我们目前的发现提示了一种独特的翻译后加工模式，这使得我们能够重新评估先前提出的一个假设，即海兔FMRF酰胺基因中的两个等效序列构成了脊椎动物促肾上腺皮质激素释放因子样肽的软体动物同源物。
