Yoshimura Masami, Pearson Susan, Kadota Yoichi, Gonzalez Cristina E
Department of Pharmacology, University of Colorado Health Sciences Center, Aurora, CO, USA.
Alcohol Clin Exp Res. 2006 Nov;30(11):1824-32. doi: 10.1111/j.1530-0277.2006.00219.x.
The activity of adenylyl cyclase (AC) is enhanced by pharmacologically relevant concentrations of ethanol. The enhancing effect of ethanol on AC activity is AC isoform-specific. Therefore, we hypothesized that within a cyclic AMP-generating system, AC is the target of ethanol's action and that ethanol-sensitive AC molecules contain structural elements modulated by ethanol. The structural elements are designated as "ethanol responsive domains."
By using a series of chimeric mutants, we searched regions of the AC molecule that are important for the ethanol effect. These chimeric mutants were derived from 3 isoforms of AC: AC7 (type 7), the most ethanol responsive isoform; AC3 (type 3), an isoform that is far less responsive to ethanol; and AC2 (type 2), an isoform that is homologous to AC7 but less responsive to ethanol.
We identified 2 discrete regions of the AC molecule that are important for the enhancement of AC activity by ethanol. The first is the N-terminal 28-amino-acid (aa) region of the C(1a) domain. The second is the C-terminal region ( approximately 140 aa) of the AC molecule. Sequence differences in the N-terminal tail, 2 putative transmembrane domains, and the C(1b) domain are not important for ethanol's effect.
The current study with mammalian ACs provides a new class of alcohol-responsive protein and possibly a new mechanism of alcohol action on cellular function. The identification of ethanol responsive domains will facilitate the elucidation of the mechanisms by which ethanol enhances the activity of AC.
药理学相关浓度的乙醇可增强腺苷酸环化酶（AC）的活性。乙醇对AC活性的增强作用具有AC同工型特异性。因此，我们推测在环磷酸腺苷生成系统中，AC是乙醇作用的靶点，且乙醇敏感的AC分子含有受乙醇调节的结构元件。这些结构元件被命名为“乙醇反应域”。
通过使用一系列嵌合突变体，我们搜索了AC分子中对乙醇效应重要的区域。这些嵌合突变体源自AC的3种同工型：AC7（7型），对乙醇反应最强的同工型；AC3（3型），对乙醇反应较弱的同工型；以及AC2（2型），与AC7同源但对乙醇反应较弱的同工型。
我们确定了AC分子中2个离散区域，它们对乙醇增强AC活性很重要。第一个是C（1a）结构域的N端28个氨基酸（aa）区域。第二个是AC分子的C端区域（约140个aa）。N端尾巴、2个假定的跨膜结构域和C（1b）结构域的序列差异对乙醇的作用并不重要。
目前对哺乳动物AC的研究提供了一类新的酒精反应蛋白，可能还有酒精对细胞功能作用的新机制。乙醇反应域的鉴定将有助于阐明乙醇增强AC活性的机制。
