Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
FEBS Lett. 2012 Sep 21;586(19):3172-8. doi: 10.1016/j.febslet.2012.06.029. Epub 2012 Jul 5.
We have identified 15 residues from the surface of sarcoplasmic reticulum Ca(2+)-pump ATPase, by mass spectrometry using diethylpyrocarbonate modification. The reactivity of 9 residues remained high under all the conditions. The reactivity of Lys-515 at the nucleotide site was severely inhibited by ATP, whereas that of Lys-158 in the A-domain decreased by one-half and increased by five-fold in the presence of Ca(2+) and MgF(4), respectively. These are well explained by solvent accessibility, pK(a) and nearby hydrophobicity of the reactive atom on the basis of the atomic structure. However, the reactivity of 4 residues near the interface among A-, N- and P-domain suggested larger conformational changes of these domains in membrane upon binding of Ca(2+) (Lys-436), ATP (Lys-158) and MgF(4) (His-5, -190, Lys-436).
我们通过使用二乙基焦碳酸酯修饰，从肌浆网 Ca(2+) -泵 ATP 酶的表面鉴定了 15 个残基。在所有条件下，9 个残基的反应性仍然很高。核苷酸部位的 Lys-515 的反应性被 ATP 严重抑制，而 A 结构域中的 Lys-158 在 Ca(2+)和 MgF(4)存在下分别降低一半和增加五倍。根据原子结构，这些都可以很好地解释为反应原子的溶剂可及性、pK(a)和附近疏水性。然而，A、N 和 P 结构域之间界面附近的 4 个残基的反应性表明，在 Ca(2+)（Lys-436）、ATP（Lys-158）和 MgF(4)（His-5、-190、Lys-436）结合时，这些结构域在膜中的构象变化更大。
