Thorndyke M, Dockray G J
Regul Pept. 1986 Dec 30;16(3-4):269-79. doi: 10.1016/0167-0115(86)90026-1.
Little is known of the identity of gastrin/cholecystokinin (CCK)-like peptides in protochordates. These animals are at a level of organization corresponding to that from which the vertebrate line arose; in order to shed light on the origins of gastrin/CCK-like peptides, we have studied by immunochemical methods these peptides in a protochordate, Ciona intestinalis. In radioimmunoassay, boiling water extracts of the neural ganglion reacted with C-terminal specific gastrin/CCK antibodies, but not N-terminal or intact G17 specific antibodies. Of particular importance was the fact that a gastrin antibody which reacts weakly with CCK8 showed full activity with the Ciona material, suggesting that it resembles the C-terminus of gastrin. A single major peak was found by gel filtration and HPLC. In immunohistochemistry, nerve cell bodies were found in the cortical regions of the ganglion, and abundant fibres ramified in the central neuropile. We conclude that peptides of the gastrin/CCK series occur in nervous tissue in protochordates, and that while they are distinguishable from known forms of both gastrin and CCK, they resemble C-terminal fragments of the mammalian gastrins.
关于原索动物中胃泌素/胆囊收缩素（CCK）样肽的特性，人们了解甚少。这些动物的组织结构层次与脊椎动物进化分支的起源层次相当；为了阐明胃泌素/CCK样肽的起源，我们采用免疫化学方法对一种原索动物——海鞘进行了研究。在放射免疫分析中，神经节的沸水提取物与C末端特异性胃泌素/CCK抗体发生反应，但不与N末端或完整的G17特异性抗体反应。特别重要的是，一种与CCK8反应较弱的胃泌素抗体对海鞘物质具有完全活性，这表明它类似于胃泌素的C末端。通过凝胶过滤和高效液相色谱法发现了一个单一的主要峰。在免疫组织化学中，在神经节的皮质区域发现了神经细胞体，并且在中央神经纤维网中有丰富的分支纤维。我们得出结论，胃泌素/CCK系列肽存在于原索动物的神经组织中，虽然它们与已知形式的胃泌素和CCK不同，但它们类似于哺乳动物胃泌素的C末端片段。
