GUANINE NUCLEOTIDE BINDING PROTEIN BETA-GAMMA DIMERS--STRUCTURE AND FUNCTION

鸟嘌呤核苷酸结合调节蛋白（G蛋白）是 α-1-β-1-γ-1异源三聚体，其作为跨膜 通过将细胞外刺激的受体偶联到 细胞内效应物（酶、离子通道）。 G蛋白组成 一个以特异性受体和效应子为特征的多样化家族 相互作用，这反过来又取决于三个结构 组成亚单位。 α亚基结合鸟嘌呤核苷酸， 在效应物调节中具有公认的作用。 β和γ 亚基紧密结合为β/γ复合物，包括 单个功能实体，就像α亚基一样， G蛋白与受体相互作用所必需的。 一种效应调节剂， β/γ复合体的作用越来越明显， 几个系统。 目前的研究强调的作用 G蛋白介导的信号转导中的β/γ复合物。 我们有 使用亚单位特异性肽抗体来探测 β/γ复合物对于与α的功能性相互作用很重要 亚基和监测重组亚基的表达。 定点 诱变已被用于研究组装，加工和效应器 β/γ复合体在瞬态和稳态中的作用 转染的细胞系统。 这些研究可以阐明 β/γ亚单位与受体的复合物和效应物选择性 G蛋白的特征和适应性反应， 激动剂刺激

The guanine-nucleotide binding regulatory proteins (G-proteins) are alpha-1-beta-1-gamma-1 heterotrimers which function as transmembrane signal transducers by coupling receptors for extracellular stimuli to intracellular effectors (enzymes, ion channels). G-proteins constitute a diverse family distinguished by specific receptor and effector interactions which in turn are determined by the structure of the three constituent subunits. The alpha subunit binds guanine nucleotides and has a well established role in effector modulation. The beta and gamma subunits are tightly associated as a beta/gamma complex, comprising a single functional entity which, like the alpha subunit, is absolutely required for G-protein interaction with receptor. An effector modulatory role for the beta/gamma complex s becoming increasingly apparent in several systems. The present research emphasizes the role of the beta/gamma complex in G-protein-mediated signal transduction. We have used subunit specific peptide antibodies to probe regions of the beta/gamma complex important for functional interaction with the alpha subunit and to monitor expression of recombinant subunits. Site-directed mutagenesis has been used to study the assembly, processing and effector function of the beta/gamma complex in both transient and stable transfected cell systems. The studies may elucidate the contribution of the beta/gamma subunit complex to the receptor and effector selectivity characteristic of G-proteins and to the adaptive responses pursuant to agonist stimulation.