Benaim G, Zurini M, Carafoli E
J Biol Chem. 1984 Jul 10;259(13):8471-7.
The purified Ca2+-pumping ATPase of the erythrocyte membrane has been exposed to trypsin at 37 degrees C, in the presence of different effectors of its activity. The control proteolytic pattern is characterized by a number of transient and of limit polypeptides (Zurini, M., Krebs, J., Penniston, J. T., and Carafoli, E. (1984) J. Biol. Chem. 259, 618-627). The effectors influence the pattern in the Mr region 90,000-76,000, which contains the calmodulin binding domain and the active site of the enzyme. In this region, polypeptides of 90, 85, 81, and 76 kDa are clearly visible in the controls. 1) Calmodulin plus Ca2+ induces the faster disappearance of the 90-kDa product and the relative accumulation of the 85-kDa with respect to the 81-kDa polypeptide. 2) Vanadate plus Mg2+ also accelerates the disappearance of the 90-kDa product. However, they induce the relative accumulation of the 81-kDa polypeptide. 3) Linoleic acid, which stimulates the activity of the enzyme to the same levels obtained with calmodulin, greatly accelerates the rate of trypsin proteolysis, causing the virtual disappearance of all polypeptides in the 90-76-kDa region. 4) The 81-kDa polypeptide has maximal ATPase activity and is insensitive to calmodulin; the 85-kDa polypeptide has lower ATPase activity and binds calmodulin, but is not stimulated (or is stimulated only negligibly) by the activator.
红细胞膜纯化的钙离子泵ATP酶在37℃下，于其活性的不同效应物存在时，用胰蛋白酶处理。对照蛋白水解模式的特征是有许多瞬时和终末多肽（Zurini, M., Krebs, J., Penniston, J. T., and Carafoli, E. (1984) J. Biol. Chem. 259, 618 - 627）。效应物影响90,000 - 76,000 Mr区域的模式，该区域包含钙调蛋白结合结构域和酶的活性位点。在该区域，对照中90、85、81和76 kDa的多肽清晰可见。1）钙调蛋白加钙离子导致90 kDa产物更快消失，且相对于81 kDa多肽，85 kDa多肽相对积累。2）钒酸盐加镁离子也加速90 kDa产物的消失。然而，它们导致81 kDa多肽相对积累。3）亚油酸可将酶的活性刺激到与钙调蛋白相同的水平，极大地加速胰蛋白酶的蛋白水解速率，导致90 - 76 kDa区域的所有多肽几乎消失。4）81 kDa多肽具有最大的ATP酶活性，对钙调蛋白不敏感；85 kDa多肽具有较低的ATP酶活性，能结合钙调蛋白，但不受激活剂刺激（或仅受到可忽略不计的刺激）。
