Type VIII adenylyl cyclase. A Ca2+/calmodulin-stimulated enzyme expressed in discrete regions of rat brain.
Type VIII adenylyl cyclase. A Ca2+/calmodulin-stimulated enzyme expressed in discrete regions of rat brain.
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发表时间：
1994-04
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通讯作者：
J. Cali;J. Zwaagstra;N. Mons;D. Cooper;J. Krupinski
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作者：
J. Cali;J. Zwaagstra;N. Mons;D. Cooper;J. Krupinski
已从两个大鼠脑文库中分离出编码VIII型腺苷酸环化酶的cDNA。开放阅读框编码一个1248个氨基酸的蛋白质，预测具有两组六个跨膜跨度和两个推定的核苷酸结合结构域，这是其他哺乳动物腺苷酸环化酶的特征。在大鼠脑中检测到两种VIII型信息，估计大小为5.5和4.4个碱基。原位杂交结果表明，VIII型信息在齿状回的颗粒细胞、海马CA 1-CA 3区的锥体细胞、内嗅皮质和梨状皮质中表达最丰富。在新皮质、杏仁复合体、丘脑和下丘脑的区域也可以检测到杂交。在人胚肾细胞中稳定表达VIII型cDNA导致膜组分中出现一种新的165-kDa糖蛋白。用增加细胞内Ca 2+的试剂刺激这些细胞导致cAMP积累比用表达载体转染的对照细胞增加高达43倍。单独添加异丙肾上腺素不会导致完整细胞中的VIII型特异性效应。腺苷酸环化酶活性在膜制备VIII型转化细胞的刺激高达40倍，通过添加钙/钙调蛋白（EC 50 = 53 nM钙调蛋白）。添加活化的重组Gs α亚基协同增加了Ca 2 +/钙调素刺激的活性。VIII型腺苷酸环化酶在长时程增强的可能作用进行了讨论。
A cDNA that encodes type VIII adenylyl cyclase has been isolated from two rat brain libraries. The open reading frame encodes a 1248-amino acid protein predicted to have two sets of six transmembrane spans and two putative nucleotide binding domains as is characteristic of other mammalian adenylyl cyclases. Two type VIII messages are detected in rat brain with estimated sizes of 5.5 and 4.4 kilobases. In situ hybridization indicates that the type VIII messages are most abundantly expressed in the granule cells of the dentate gyrus, the pyramidal cells of hippocampal fields CA1-CA3, the entorhinal cortex, and the piriform cortex. Hybridization is also detected in the neocortex, the amygdaloid complex, and regions of the thalamus and hypothalamus. Stable expression of the type VIII cDNA in human embryonal kidney cells leads to the appearance of a novel 165-kDa glycoprotein in the membrane fraction. Stimulation of these cells with agents that increase intracellular Ca2+ results in up to 43-fold increases in cAMP accumulation over that of control cells transfected with the expression vector. Addition of isoproterenol alone does not lead to type VIII-specific effects in intact cells. Adenylyl cyclase activity in membranes prepared from type VIII-transformed cells is stimulated up to 40-fold by the addition of Ca2+/calmodulin (EC50 = 53 nM calmodulin). The addition of activated recombinant alpha subunit of Gs synergistically increases the Ca2+/calmodulin-stimulated activity. A possible role for type VIII adenylyl cyclase in long-term potentiation is discussed.