Molecular and Functional Characterization of Neuronal FMRFamide-Activated Channels

组成动物的许多细胞通过化学信号相互交流。一个细胞释放一种化学物质，通过这种化学物质与细胞表面的“受体”蛋白的相互作用，另一个细胞可以检测到这种化学物质。受体必须将外部信号传递到细胞内部，通常是通过在细胞表面打开一个选择性的孔，让特定的带电离子进出细胞。选择性孔被称为“离子通道”，受体被称为通道的“门”。这种信号在神经系统中特别复杂，但离子通道也参与盐和水的平衡，在肾脏中尤其丰富。其中一个肾通道被称为上皮钠通道因为它允许钠离子通过。在神经系统中，上皮钠通道被认为与介导化学信号传递的钠通道完全不同，但最近有研究表明，神经系统中有一类通道与上皮钠通道有关。在蜗牛螺旋中，一个来自神经系统的上皮钠通道被一种名为FMRFamide的特殊化学物质控制。FMRFamide是由某些神经细胞释放的肽，因此是一组被称为神经肽的信号分子的一个例子。FMRFamide是唯一已知的直接控制离子通道的神经肽，它所控制的通道是唯一已知的由神经细胞释放的物质（即“神经递质”）控制的上皮钠通道。普莱斯博士从海蛞蝓（一种与陆地蜗牛Helix有亲缘关系的动物，但其神经系统的研究比Helix要广泛得多）中克隆了两个上皮钠通道的部分。现在，他将尝试分离出包含这两个通道的全长克隆（含有来自applysia的基因的培养细胞），以便确定它们的物理特性，并将它们在神经系统中的定位与已知的FMRFamide的定位进行比较。这些研究的最终结果将是更好地理解神经肽如何参与动物个体神经细胞的交流，以及这种交流如何介导即使是最简单的动物也表现出的复杂行为。

IBN 98-10804 PRICE Many of the cells that compose an animal communicate with each other by means of chemical signals. One cell releases a chemical which is detected by another cell through the interaction of the chemical with a "receptor" protein on the cell's surface. The receptor must pass the external signal into the interior of the cell and often does so by opening a selective pore in the cell's surface which lets particular charged ions into and out of the cell. The selective pore is called an "ion channel" and the receptor is said to "gate" the channel. Such signaling is especially elaborate in the nervous system, but ion channels are also involved in salt and water balance and are particularly abundant in the kidney. One of the kidney channels is called the epithelial sodium channel because it allows the sodium ion to pass. It was thought that the epithelial sodium channels were completely distinct from sodium channels mediating chemical signal transmission in the nervous system, but it has recently been shown that one type of channel in the nervous system is related to the epithelial sodium channels. In the snail Helix, one such epithelial sodium-channel relative from the nervous system is gated by a particular chemical named FMRFamide. FMRFamide is a peptide released by certain nerve cells and is thus one example of a group of signaling molecules known as neuropeptides. FMRFamide is the only neuropeptide known to directly gate an ion channel and the channel it gates is the only epithelial sodium channel relative known to be gated by a substance released by nerve cells (i.e. by a "neurotransmitter"). Dr. Price has cloned portions of two epithelial sodium channels from the sea slug Aplysia (an animal related to the land-snail, Helix, but with a much more extensively studied nervous system than Helix). He will now try to isolate full length clones (cultured cells containing the gene from Aplysia) containing these two channels so that their physica l properties can be determined and also so that their localization in the nervous system can be compared to the known localization of FMRFamide. The end result of these studies will be a better understanding of how neuropeptides are involved in the communication of individual nerve cells of an animal and how such communication mediates the complex behaviors that even the most simple animals exhibit.