Yan K, Gautam N
Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Biol Chem. 1996 Jul 26;271(30):17597-600. doi: 10.1074/jbc.271.30.17597.
The G protein betagamma complex modulates the function of a variety of effectors in biological signaling. However, the individual roles of the beta and gamma subunits in this interaction are unknown. Unlike in the case of the alpha subunit, domains on the betagamma complex that contact effectors have not yet been identified. We show here using the yeast two-hybrid system that the beta subunit and not the gamma subunit interacts with domains specific to adenylyl cyclase type 2 (AC2) and the muscarinic receptor-gated atrial inwardly rectifying potassium channel, GIRK1. Different beta subunit types interact with these effector domains with different efficacies. Furthermore, an N-terminal fragment of 100 residues interacts with both these effector domains as effectively as the whole beta subunit. This domain includes the region where the beta subunit contacts with the alpha subunit in the crystal structure and may therefore explain the ability of the alpha subunit to shut off the activity of the betagamma complex.
G蛋白βγ复合物在生物信号传导中调节多种效应器的功能。然而，β和γ亚基在这种相互作用中的各自作用尚不清楚。与α亚基不同，βγ复合物上与效应器接触的结构域尚未确定。我们在此使用酵母双杂交系统表明，与效应器相互作用的是β亚基而非γ亚基，这些效应器包括2型腺苷酸环化酶（AC2）和毒蕈碱受体门控的心房内向整流钾通道GIRK1的特异性结构域。不同类型的β亚基与这些效应器结构域相互作用的效率不同。此外，一个100个残基的N端片段与这两个效应器结构域的相互作用效果与整个β亚基一样有效。该结构域包括晶体结构中β亚基与α亚基接触的区域，因此可能解释了α亚基关闭βγ复合物活性的能力。
