Organization of G proteins and adenylyl cyclase at the plasma membrane
Organization of G proteins and adenylyl cyclase at the plasma membrane
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DOI：
10.1091/mbc.8.12.2365
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发表时间：
1997-12-01
影响因子：
3.3
通讯作者：
Mumby, SM
中科院分区：
文献类型：
--
作者：
Huang, CF;Hepler, JR;Mumby, SM
有越来越多的证据表明，信号分子在质膜上是组织和分隔的。我们发现，激素敏感的腺酰环化酶活性在质膜中含有G蛋白的调节组分中得到了丰富。这些亚组分在低浮力密度下类似于质膜的结构，称为小窝。免疫荧光实验显示G蛋白α和β亚基呈点状分布，与这些蛋白在质膜上不同位置的浓度一致。免疫荧光双标记法观察到G蛋白α亚基与小窝蛋白的定位部分一致。免疫金电镜结果显示，部分G蛋白与内陷小窝有关，但大多数G蛋白存在于质膜的不规则结构中，形态上无法识别。因为在一种不表达小窝蛋白的细胞型(S49淋巴瘤)的质膜低密度亚组分中存在受调控的腺酰环化酶活性，该蛋白不是腺酰环化酶系统组织所必需的。这些数据表明，激素敏感的腺酰环化酶系统定位于质膜的一个专门的亚区，可能优化信号转导的效率和保真度。
There is mounting evidence for the organization and compartmentation of signaling molecules at the plasma membrane. We find that hormone-sensitive adenylyl cyclase activity is enriched in a subset of regulatory G protein-containing fractions of the plasma membrane. These subfractions resemble, in low buoyant density, structures of the plasma membrane termed caveolae. Immunofluorescence experiments revealed a punctate pattern of G protein alpha and beta subunits, consistent with concentration of these proteins at distinct sites on the plasma membrane. Partial coincidence of localization of G protein alpha subunits with caveolin (a marker for caveolae) was observed by double immunofluorescence. Results of immunogold electron microscopy suggest that some G protein is associated with invaginated caveolae, but most of the protein resides in irregular structures of the plasma membrane that could not be identified morphologically. Because regulated adenylyl cyclase activity is present in low-density subfractions of plasma membrane from a cell type (S49 lymphoma) that does not express caveolin, this protein is not required for organization of the adenylyl cyclase system. The data suggest that hormone-sensitive adenylyl cyclase systems are localized in a specialized subdomain of the plasma membrane that may optimize the efficiency and fidelity of signal transduction.