平滑肌中存在两种钙转运ATP酶的证据。

Wuytack F, Raeymaekers L, Verbist J, De Smedt H, Casteels R

Biochem J. 1984 Dec 1;224(2):445-51. doi: 10.1042/bj2240445.

Membrane fractions prepared from smooth muscle of the pig stomach (antral part) contain two Ca2+-dependent phosphoprotein intermediates belonging to different Ca2+-transport ATPases. These alkali-labile phosphoproteins can be separated by electrophoresis in acid medium. The 130 kDa phosphoprotein resembles a corresponding protein in the erythrocyte membrane, whereas the 100 kDa protein resembles that of the Ca2+-transport ATPase in sarcoplasmic reticulum from skeletal muscle. These resemblances are expressed in terms of Mr, reaction to La3+ and in a similar proteolytic degradation pattern. The presence of the calmodulin-stimulated ATPase in mixed membranes from smooth muscle is confirmed by its binding of calmodulin and antibodies against erythrocyte Ca2+-transport ATPase, whereas such binding does not occur with proteins present in the presumed endoplasmic reticulum from smooth muscle.

从猪胃（胃窦部）平滑肌制备的膜组分含有两种属于不同Ca2+转运ATP酶的Ca2+依赖性磷蛋白中间体。这些对碱不稳定的磷蛋白可通过在酸性介质中进行电泳分离。130 kDa的磷蛋白类似于红细胞膜中的相应蛋白，而100 kDa的蛋白类似于骨骼肌肌浆网中Ca2+转运ATP酶的蛋白。这些相似性体现在分子量、对La3+的反应以及相似的蛋白水解降解模式方面。平滑肌混合膜中钙调蛋白刺激的ATP酶通过其与钙调蛋白和抗红细胞Ca2+转运ATP酶抗体的结合得到证实，而假定的平滑肌内质网中存在的蛋白质则不会发生这种结合。