Montell C
Department of Biological Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.
Curr Opin Neurobiol. 1998 Jun;8(3):389-97. doi: 10.1016/s0959-4388(98)80066-4.
In the Drosophila eye, photoactivation of rhodopsin leads to the opening of the light-sensitive cation influx channels TRP and TRPL. This response is extremely rapid and results in depolarization of the photoreceptor cells followed by Ca(2+)-mediated feedback regulation of the visual signaling cascade. The mechanisms that facilitate the rapid kinetics of activation and feedback regulation are poorly understood. However, the recent discovery that most of the proteins that function in fly phototransduction associate into a supramolecular complex permits a re-evaluation of the mechanisms underlying the activation and regulation of the cascade. The central player in the signaling complex is INAD, a protein with five protein-interaction motifs known as PDZ domains. The INAD complex does not appear to be a particle, but a massive signaling web composed of an INAD polymer with which some of the target proteins associate through complex multivalent interactions.
在果蝇眼中，视紫红质的光激活导致光敏阳离子流入通道TRP和TRPL开放。这种反应极其迅速，导致光感受器细胞去极化，随后是视觉信号级联反应的Ca(2+)介导的反馈调节。促进激活和反馈调节快速动力学的机制尚不清楚。然而，最近的发现表明，在果蝇光转导中起作用的大多数蛋白质会结合形成一个超分子复合物，这使得人们可以重新评估级联反应激活和调节的潜在机制。信号复合物中的核心成分是INAD，一种具有五个蛋白质相互作用基序（称为PDZ结构域）的蛋白质。INAD复合物似乎不是一个颗粒，而是一个由INAD聚合物组成的庞大信号网络，一些靶蛋白通过复杂的多价相互作用与之结合。
