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Specific interaction of FK506 binding protein (FKBP) isoforms with the ryanodine/CaィイD12+ィエD1 release channel subtypes

FK506 结合蛋白 (FKBP) 亚型与兰尼定/CaD12+D1 释放通道亚型的特异性相互作用

基本信息

批准号：
10470024
负责人：
ITO Yushi
金额：
$ 8.06万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The calcium release channels (CRC)/ryanodine receptor of skeletal (Sk) and (C) muscle sarcoplasmic reticulum (SR) are hetero-oligomeric complexes with the structural formulas (ryanodine receptor(RYR)1 receptor)ィイD24ィエD2 (FKBP12)ィイD24ィエD2 and (RYP2 protomer)ィイD24ィエD2 (FKBP12.6)ィイD24ィエD2, respectively, where FKBP12 and FKBP12.6 are isoforms of the 12-kDa receptor for the immunosuppressant drug FK506. Using ィイD135ィエD1S-labeled FKBP12 and ィイD135ィエD1S-labeled FKBP12.6 as probes to study the interaction with CRC, we find that : 1) analogous to its action in skeletal muscle sarcoplasmic reticulum (SkMSR), FK506 dissociates FKBP12.6 from CSR ; 2) both FKBP isoforms bind to FKBP-stripped SkMSR and exchange with endogenously bound FKBP12 of SkMSR ; and 3) by contrast, only FKBP12.6 exchanges with endogenously bound FKBP12.6 or rebinds to FKBP-stripped CSR. This selective binding appears to explain why the cardiac CRC is isolated as a complex with FKBP12.6, whereas the skeletal muscle CRC is isolated as a complex with FKBP12.6 although only FKBP12 is detectable in the myoplasm of both muscle types. In contrast to the activation of the channel by removal of FKBP from skeletal muscle, no activation is detected in CRC activity in FKBP-stripped CSR. This deferential action of FKBP may reflect a fundamental difference in the modulation of excitation-contraction coupling in heart versus skeletal muscle.we also examined whether FKBP is associated with the RYR in situ by immunolocalization studies. In rat skeletal muscle section, both the RYR and FKBP were detected as transverse bands with periodicity along the full length of the muscle fiber. When the same section was dual-proved with anti-RYR and anti-FKBP antibody, the bands of FKBP superimposed upon the bands of the RYR. These results suggest that FKBP is associated with the RYR in situ and modulates the function of the RYR/CRC in skeletal muscle.

骨骼肌（Sk）和（C）肌肌浆网（SR）的钙释放通道（CRC）/兰尼碱受体是具有以下结构式的异源寡聚复合物：（ryanodine receptor（RYR）1 receptor）FKBP D24 FKBP D2（FKBP 12）FKBP D24 FKBP D2和（RYP 2原聚体）FKBP D24 FKBP D2（FKBP 12.6）FKBP D24 FKBP D2，其中FKBP 12和FKBP 12.6是免疫抑制药物FK 506的12-kDa受体的同种型。以FK 506和FKBP12.6为探针，研究了FKBP 12和FKBP12.6与CRC的相互作用，结果发现：1）FK 506与骨骼肌肌浆网（SkMSR）的作用相似，能使FKBP12.6从CSR中解离出来;和3）相反，只有FKBP 12.6与内源性结合的FKBP 12.6交换或与FKBP剥离的CSR重新结合。这种选择性结合似乎解释了为什么心脏CRC被分离为与FKBP 12.6的复合物，而骨骼肌CRC被分离为与FKBP 12.6的复合物，尽管在两种肌肉类型的肌浆中仅可检测到FKBP 12。与通过从骨骼肌去除FKBP激活通道相反，在FKBP剥离的CSR中未检测到CRC活性的激活。FKBP的这种差异性作用可能反映了心脏与骨骼肌兴奋-收缩偶联调节的根本差异。我们还通过免疫定位研究研究了FKBP是否与RYR原位相关。在大鼠骨骼肌切片中，RYR和FKBP都被检测为沿肌纤维全长具有沿着周期性的横向条带。当用抗RYR和抗FKBP抗体对同一切片进行双重鉴定时，FKBP的条带与RYR的条带重叠。这些结果表明，FKBP与RYR在原位和调节骨骼肌中的RYR/CRC的功能。