Gaburjakova M, Gaburjakova J, Reiken S, Huang F, Marx S O, Rosemblit N, Marks A R
Center for Molecular Cardiology and Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
J Biol Chem. 2001 May 18;276(20):16931-5. doi: 10.1074/jbc.M100856200. Epub 2001 Mar 1.
The ryanodine receptor (RyR1)/calcium release channel on the sarcoplasmic reticulum of skeletal muscle is comprised of four 565,000-dalton RyR1s, each of which binds one FK506 binding protein (FKBP12). RyR1 is required for excitation-contraction coupling in skeletal muscle. FKBP12, a cis-trans peptidyl-prolyl isomerase, is required for the normal gating of the RyR1 channel. In the absence of FKBP12, RyR1 channels exhibit increased gating frequency, suggesting that FKBP12 "stabilizes" the channel in the open and closed states. We now show that substitution of a Gly, Glu, or Ile for Val2461 in RyR1 prevents FKBP12 binding to RyR1, resulting in channels with increased gating frequency. In the case of the V2461I mutant RyR1, normal channel function can be restored by adding FKBP12.6, an isoform of FKBP12. These data identify Val2461 as a critical residue required for FKBP12 binding to RyR1 and demonstrate the functional role for FKBP12 in the RyR1 channel complex.
骨骼肌肌浆网上的兰尼碱受体（RyR1）/钙释放通道由四个565,000道尔顿的RyR1组成，每个RyR1结合一个FK506结合蛋白（FKBP12）。RyR1是骨骼肌兴奋-收缩偶联所必需的。FKBP12是一种顺反肽基脯氨酰异构酶，是RyR1通道正常门控所必需的。在没有FKBP12的情况下，RyR1通道表现出门控频率增加，这表明FKBP12在开放和关闭状态下“稳定”了通道。我们现在表明，用甘氨酸、谷氨酸或异亮氨酸取代RyR1中的Val2461会阻止FKBP12与RyR1结合，导致通道门控频率增加。对于V2461I突变体RyR1，通过添加FKBP12的一种同工型FKBP12.6可以恢复正常的通道功能。这些数据确定Val2461是FKBP12与RyR1结合所需的关键残基，并证明了FKBP12在RyR1通道复合物中的功能作用。
