Identification of novel ghrelin receptor in fish and clarification of the relationship between the receptor and biological action.

本研究从金鱼脑中克隆了四种具有生长激素释放肽功能的受体（GHS-R1 a-1、1a-2、2a-1和2a-2）的cDNA，它们分别由360、360、366和367个氨基酸组成。每个受体的mRNA表现出组织特异性表达，表明每个受体介导的组织特异性作用的生长激素释放肽在金鱼。生长激素释放肽受体GHS-R1 a是目前已知的存在于脊椎动物中的一种受体，而不是鱼类。我们试图从金鱼脑和肠的组织提取物中分离新的功能性GHS-Ra的新配体，GHS-Ra是一种新型的生长激素释放肽受体，但不幸的是，在本研究过程中未能发现新的配体。

In this study, we cloned cDNAs for four functional ghrelin receptors (GHS-R1a-1, 1a-2, 2a-1 and 2a-2) that composed of 360, 360, 366 and 367 amino acids, respectively in goldfish brain. Each receptor mRNA showed tissue-specific expression, suggesting that each receptor mediates tissue-specific action of ghrelin in goldfish. One species of ghrelin receptor, GHS-R1a has been known to be present in vertebrates other than fish examined so far. We tried to isolate new ligands for the new functional GHS-Ra, which is the novel type of ghrelin receptor, from tissue extracts of goldfish brain and intestine, but unfortunately the new ligand was not able to find out during the course of this study.