MODULATION OF CALCIUM FLUXES IN HEART AND SMOOTH MUSCLE

我们正在进行的项目的长期目标是了解兴奋- 肌肉（骨骼肌、心脏和平滑肌）中的收缩（E-C偶联）。 重点是结构，功能和调节的 细胞内钙释放通道（ICRC），一类新的通道 其特征在于它们的大尺寸和四重对称性。ICRC是 在从细胞内钙库中动员细胞内Ca 2 + 信号装置.有两种类型，ryanodine受体（RyR）和IP 3 受体（IP 3R）。我们实验室最近的两项发现提供了依据 关于RyR受体调节的关键拟议研究。 1)免疫抑制剂对骶浆网末端池的磷酸化作用 蛋白激酶使通道活跃，而磷酸酶作用 使通道处于非活动状态， 生理的[Mg 2 +]。2)FK结合蛋白（FKBP）， 免疫抑制药物FK 5 O 61与兰尼碱受体紧密结合 骨骼肌（RyR-1）和心脏（RyR-2）的同种型。有七个目标： 1)表征RyR-1和RyR-2活性调节的性质 通过蛋白激酶和磷酸酶 2)研究血管紧张素Ⅱ对平滑肌IP 3受体的调节作用 用蛋白激酶/磷酸酶进行磷酸化/去磷酸化。的 实验方法类似于RyR。(See目标1）。 3)通过蛋白水解确定来自平滑肌的IP 3 R的表面拓扑结构 灵敏度绘图也就是说，完整的受体将被 选择性蛋白水解消化和所形成的肽， 化学测序每种肽都能识别 受体的表面。 4)继续进行RyR的三维结构分析研究， 心脏和骨骼肌，并启动与IP 3 R的研究（一起 Terrence Wagenknecht博士及其同事）。 5)评估的生理相关性和功能后果， FKBP与骨骼肌和心脏ryanodine的关联 受体。 6)定义FKBP和RyR受体上的表面界面， 特异性FKBP亚型与两种骨骼肌RyR的相关性 肌肉（FKBP 12/RyR 1）和心脏（FKBP-C/RyR 2） 7)评价FKBP和磷酸化/去磷酸化在 调节骨骼肌和心脏中的E-C偶联。我们的计划是 旨在关联ICRC的结构/功能关系， 它们与钙稳态和E-C偶联的生理相关性， 肌肉.

The long term goal of our ongoing program is to understand excitation- contraction (E-C) coupling in muscle (skeletal, heart and smooth muscle). The emphasis is on the structure, function and regulation of the intracellular calcium release channels (ICRCs), a new class of channels characterized by their large size and four-fold symmetry. ICRCs are important in mobilizing Ca2+ from intracellular stores for cell signalling. There are two types, the ryanodine receptor (RyR) and the IP3 receptor (IP3R). Two recent findings in our laboratory provide the basis of key proposed studies regarding the modulation of the RyR receptor. 1)Phosphorylation of terminal Cisternae of sacroplasmic reticulum by protein kinases renders the channel active, whereas phosphatase action renders the channel inactive, in the presence of approximately physiological [Mg2+].; 2) FK binding protein (FKBP), the receptor for the immunosuppressive drug FK5O61 is tightly bound to the ryanodine receptor isoforms of skeletal muscle (RyR-1) and heart (RyR-2). There are 7 aims: 1) Characterize the nature of the modulation of RyR-1 and RyR-2 activity by protein kinases and phosphatases 2) Study the modulation of the IP3 R from smooth muscle by phosphorylation/dephosphorylation with protei kinases/phosphatases. The experimental approach is similar to that for the RyR. (See Aim 1). 3) Determine surface topology of IP3 R from smooth muscle by proteolysis sensitivity mapping. That is, the intact receptor will be cleaved by selective proteolytic digestion and the peptides formed identified by chemical sequencing. Each peptide identifies a specific peptide bond on the surface of the receptor. 4) Continue three-dimensional structure analysis studies of the RyR from heart and skeletal muscle and initiate studies with the IP3 R (together with Dr. Terrence Wagenknecht and colleagues). 5) Assess the physiological relevance and functional consequence of the association of the FKBP with skeletal muscle and heart ryanodine receptors. 6) Define the surface interfaces on FKBP and on the RyR receptor in the association of specific FKBP isoforms with the RyR for both skeletal muscle (FKBP12/RyR1) and heart (FKBP-C/RyR2) 7) Evaluate the role of FKBP and phosphorylation/dephosphorylation in modulating E-C coupling in skeletal muscle and heart. Our program is designed to correlate structure/function relationships of the ICRCs and their physiological relevance to calcium homeostasis and E-C coupling in muscle.