GUANYLATE CYCLASES IN ROD PHOTORECEPTORS

杆状光感受器中的鸟苷酸环化酶

• 批准号: 3264114
• 负责人: SITARAMAYYA ARI
• 金额: $ 18.9万
• 依托单位: OAKLAND UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 1996-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3264114
• 关键词: G protein; adenosine triphosphate; antibody; binding proteins; calcium binding protein; electron microscopy; enzyme mechanism; guanylate cyclase; immunocytochemistry; laboratory rabbit; molecular cloning; phosphodiesterase inhibitors; phosphodiesterases; photoactivation; protein purification; pyrophosphatase; pyrophosphates; rod cell; visual photoreceptor; visual phototransduction

Light activation of the hydrolysis of cyclic GMP is hypothesized to transiently decrease the dark current in rod photoreceptor cells. Termination of this hydrolysis and synthesis of cyclic GMP to restore its concentration are thought to underlie the recovery of the dark current. While the biochemical reactions involved in the activation phase are understood in great detail, there are many unresolved questions about the kinetics and regulation of the reactions in the recovery phase. Guanylate cyclase, the enzyme that synthesizes cyclic GMP from GTP, plays a critical role in the recovery process. In continuing our studies on this enzyme, the proposed research will utilize biochemical, molecular biological, immunohistochemical and electron microscopic techniques to address the following questions: (1) Are there multiple cyclases in the rod photoreceptor cells? Where in the cell are they localized? (2) Are the effects of recovering and ATP on cyclase mediated by other proteins? (3) Are the cyclases regulated by phosphorylation and dephosphorylation? (4) Are the cyclases modulated by the reaction product, pyrophosphate, either directly or through a calcium mediated process involving pyrophosphatase? (5) Are the cyclases activated by light? Are the proteins of the activation phase of light response, such as PDE, G-protein, arrestin, coupled to cyclase in mediating the effects of light? The proposed research will enhance our understanding of the controls on cyclic GMP synthesis and thus on the recovery phase of the light response.

环 GMP 水解的光活化被假设为 暂时减少视杆细胞中的暗电流。 终止环 GMP 的水解和合成以恢复其 浓度被认为是暗电流恢复的基础。 虽然激活阶段涉及的生化反应是 详细了解后，还有很多未解决的问题 恢复阶段反应的动力学和调节。 鸟苷酸 环化酶是一种从 GTP 合成环 GMP 的酶，在 在恢复过程中的作用。 在继续我们对这种酶的研究时， 拟议的研究将利用生物化学、分子生物学、 免疫组织化学和电子显微镜技术来解决 以下问题：（1）杆中是否存在多种环化酶 感光细胞？它们位于细胞的哪个位置？ (2) 是 恢复和 ATP 对其他蛋白质介导的环化酶的影响？ (3) 环化酶是否受磷酸化和去磷酸化调节？ (4) 环化酶是否受反应产物焦磷酸调节？ 直接或通过涉及焦磷酸酶的钙介导过程？ (5) 环化酶是否被光激活？是激活的蛋白质吗 光反应阶段，如 PDE、G 蛋白、视紫红质抑制蛋白，偶联 环化酶介导光的影响？拟议的研究将 增强我们对环 GMP 合成控制的理解，从而 光响应的恢复阶段。