IDENTIFICATION OF A NONCATALYTIC CGMP-BINDING DOMAIN CONSERVED IN BOTH THE CGMP-STIMULATED AND PHOTORECEPTOR CYCLIC-NUCLEOTIDE PHOSPHODIESTERASES
IDENTIFICATION OF A NONCATALYTIC CGMP-BINDING DOMAIN CONSERVED IN BOTH THE CGMP-STIMULATED AND PHOTORECEPTOR CYCLIC-NUCLEOTIDE PHOSPHODIESTERASES
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DOI：
10.1073/pnas.87.1.288
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发表时间：
1990-01-01
影响因子：
11.1
通讯作者：
BEAVO, JA
中科院分区：
文献类型：
--
作者：
CHARBONNEAU, H;PRUSTI, RK;BEAVO, JA
已经确定了牛感光器环核苷酸磷酸二酯酶(PDE)锥体α''亚基的部分氨基酸序列，并从部分cDNA克隆的核苷酸序列推导出来。这些序列将“α”亚基鉴定为与编码“α”的基因不同的基因的产物。或.beta。膜相关杆光感受器 PDE 的亚基。最近确定的 cGMP 刺激的 PDE 序列与 α 序列之间的比较。和“α”光感受器PDE亚基揭示了意想不到的序列相似性。除了真核 PDE 中保守的催化结构域外，所有三个 PDE 都拥有 .apprxeq 的第二个保守片段。 340 个残基，包含两个内部同源重复序列。有限的蛋白水解和直接光标记研究表明，cGMP 刺激的 PDE 中的非催化 cGMP 结合位点位于这个保守结构域内，这表明它也可能在光感受器 PDE 中发挥这种功能。此外，在非催化位点不结合 cGMP 的其他 PDE 不包含此保守结构域。光感受器 PDE 中保守片段的功能尚不清楚，但与 cGMP 刺激的 PDE 变构位点的同源性表明其在 cGMP 结合和酶活性调节中发挥作用。
Partial amino acid sequence has been determined for the cone, .alpha.'' subunit of the bovine photoreceptor cyclic nucleotide phosphodiesterase (PDE) and deduced from nucleotide sequences of a partial cDNA clone. These sequences identify the .alpha.'' subunit as the product of a gene that is distinct from those encoding the .alpha. or .beta. subunits of the membrane-associated rod photoreceptor PDE. Comparisons between the recently determined cGMP-stimulated-PDE sequence and those of the .alpha. and .alpha.'' photoreceptor PDE subunits reveal an unexpected sequence similarity. In addition to the catalytic domain conserved in eukaryotic PDEs, all three PDEs possess a second conserved segment of .apprxeq. 340 residues that contains two internally homologous repeats. Limited proteolysis and direct photolabeling studies indicate that the noncatalytic, cGMP-binding site(s) in the cGMP-stimulated PDE is located within this conserved domain, suggesting that it also may serve this function in the photoreceptor PDEs. Moreover, other PDEs that do not bind cGMP at noncatalytic sites do not contain this conserved domain. The function of the conserved segment in the photoreceptor PDEs is not known, but the homology to allosteric sites of the cGMP-stimulated PDE suggests a role in cGMP binding and modulation of enzyme activity.