Codina J, Yatani A, Grenet D, Brown A M, Birnbaumer L
Science. 1987 Apr 24;236(4800):442-5. doi: 10.1126/science.2436299.
Guanine nucleotide binding (G) proteins (subunit composition alpha beta gamma) dissociate on activation with guanosine triphosphate (GTP) analogs and magnesium to give alpha-guanine nucleotide complexes and free beta gamma subunits. Whether the opening of potassium channels by the recently described Gk in isolated membrane patches from mammalian atrial myocytes was mediated by the alpha k subunit or beta gamma dimer was tested. The alpha k subunit was found to be active, while the beta gamma dimer was inactive in stimulating potassium channel activity. Thus, Gk resembles Gs, the stimulatory regulatory component of adenylyl cyclase, and transducin, the regulatory component of the visual system, in that it regulates its effector function--the activity of the ligand-gated potassium channel--through its guanine nucleotide binding subunit.
鸟嘌呤核苷酸结合（G）蛋白（亚基组成为αβγ）在与鸟苷三磷酸（GTP）类似物和镁离子激活时解离，产生α - 鸟嘌呤核苷酸复合物和游离的βγ亚基。在来自哺乳动物心房肌细胞的分离膜片中，最近描述的Gk对钾通道的开放是由αk亚基还是βγ二聚体介导的，对此进行了测试。结果发现αk亚基具有活性，而βγ二聚体在刺激钾通道活性方面无活性。因此，Gk类似于腺苷酸环化酶的刺激性调节成分Gs和视觉系统的调节成分转导素，即它通过其鸟嘌呤核苷酸结合亚基调节其效应器功能——配体门控钾通道的活性。
