An autoinhibitory peptide from the erythrocyte Ca-ATPase aggregates and inhibits both muscle Ca-ATPase isoforms.
An autoinhibitory peptide from the erythrocyte Ca-ATPase aggregates and inhibits both muscle Ca-ATPase isoforms.
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来自红细胞 Ca-ATP 酶的自抑制肽聚集并抑制肌肉 Ca-ATP 酶亚型。
DOI：
10.1016/s0006-3495(99)77458-8
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Thomas,DD
中科院分区：
文献类型：
--
作者：
Reddy,LG;Shi,Y;Kutchai,H;Filoteo,AG;Penniston,JT;Thomas,DD
我们研究了C28R2（一种来源于质膜ca - atp酶自抑制区域的碱性肽）对骨骼和心脏肌浆网ca - atp酶的酶活性、寡聚态和E1-E2构象平衡的影响。利用时间分辨磷光各向异性（TPA）测定SR. C28R2中Ca-ATPase在其不同寡聚物种间的分布变化，在1-10μM浓度下，Ca-ATPase在骨骼和心脏SR （CSR）中均有抑制作用。在骨骼SR中，C28R2在低（0.15μM） Ca2+下的抑制作用远大于高（10μM） Ca2+下的抑制作用，而在CSR中，低和高Ca2+下的抑制作用是相同的。肽对Ca-ATPase旋转迁移率的影响与功能密切相关，表明c28r2诱导的蛋白质聚集和Ca-ATPase抑制在骨骼中比在CSR中更依赖于ca。在低Ca2+的CSR中，phospholamban （PLB）抗体（功能相当于PLB磷酸化）略微增强了C28R2的抑制作用。荧光素5-异硫氰酸酯标记SR的荧光表明，C28R2稳定了骨骼SR中ca - atp酶的E1构象，而在CSR中它稳定了E2构象。加入PLB抗体后，C28R2仍能稳定CSR的E2构象态。因此，我们得出结论，C28R2在心脏和骨骼SR中对ca - atp酶活性、构象和自我关联的影响不同，PLB可能不是造成差异的原因。
We have studied the effects of C28R2, a basic peptide derived from the autoinhibitory domain of the plasma membrane Ca-ATPase, on enzyme activity, oligomeric state, and E1-E2 conformational equilibrium of the Ca-ATPase from skeletal and cardiac sarcoplasmic reticulum (SR). Time-resolved phosphorescence anisotropy (TPA) was used to determine changes in the distribution of Ca-ATPase among its different oligomeric species in SR. C28R2, at a concentration of 1–10μM, inhibits the Ca-ATPase activity of both skeletal and cardiac SR (CSR). In skeletal SR, this inhibition by C28R2 is much greater at low (0.15μM) than at high (10μM) Ca2+, whereas in CSR the inhibition is the same at low and high Ca2+. The effects of the peptide on the rotational mobility of the Ca-ATPase correlated well with function, indicating that C28R2-induced protein aggregation and Ca-ATPase inhibition are much more Ca-dependent in skeletal than in CSR. In CSR at low Ca2+, phospholamban (PLB) antibody (functionally equivalent to PLB phosphorylation) increased the inhibitory effect of C28R2 slightly. Fluorescence of fluorescein 5-isothiocyanate-labeled SR suggests that C28R2 stabilizes the E1 conformation of the Ca-ATPase in skeletal SR, whereas in CSR it stabilizes E2. After the addition of PLB antibody, C28R2 still stabilizes the E2 conformational state of CSR. Therefore, we conclude that C28R2 affects Ca-ATPase activity, conformation, and self-association differently in cardiac and skeletal SR and that PLB is probably not responsible for the differences.