Santella L, Kyozuka K, De Riso L, Carafoli E
Stazione Zoologica A. Dohrn, Napoli, Italy.
Cell Calcium. 1998 Feb-Mar;23(2-3):123-30. doi: 10.1016/s0143-4160(98)90110-5.
Proteolysis is a key event in the control of the cell cycle. Most of the proteins which are degraded at specific cycle points, e.g. cyclins A, B, and E, are substrates of the ubiquitin/proteasome pathway. The Ca2+ dependent neutral protease calpain also cleaves cell cycle proteins, among them cyclin D1 and the c-mos proto-oncogene product which is a component of the CSF. The proteasome itself, however, may be under Ca2+ control through the binding of Ca2+ to its 29 kDa regulatory subunit. Calpain undergoes relocation among cell compartments during the various steps of the mitotic and meitotic cycles. It promotes the initiation and the progression of mitosis when injected into the perinuclear space of synchronized PtK1 cells, and the resumption of meiosis when directly injected into the nuclei of prophase-arrested starfish oocytes. Apart from the proteins mentioned above, most of the substrates of calpain which become cleaved during mitosis and meiosis are still unknown. Microtubule-associated proteins are likely candidates.
蛋白质水解是细胞周期调控中的关键事件。在特定周期点被降解的大多数蛋白质，如细胞周期蛋白A、B和E，都是泛素/蛋白酶体途径的底物。钙离子依赖性中性蛋白酶钙蛋白酶也能切割细胞周期蛋白，其中包括细胞周期蛋白D1和原癌基因c-mos的产物，后者是细胞静止因子的一个组成部分。然而，蛋白酶体本身可能通过钙离子与其29 kDa调节亚基的结合而受到钙离子的控制。在有丝分裂和减数分裂周期的各个阶段，钙蛋白酶会在细胞区室之间重新定位。当注入同步化的PtK1细胞的核周空间时，它会促进有丝分裂的启动和进程；当直接注入前期停滞的海星卵母细胞核时，它会促进减数分裂的恢复。除了上述蛋白质外，在有丝分裂和减数分裂过程中被钙蛋白酶切割的大多数底物仍然未知。微管相关蛋白可能是候选底物。
