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Apoptosis (apoptosis) is a multi-cellular organisms body cells in the physiological or pathological state of a spontaneous programmed cell death process, a normal event in the development and mature individuals maintain homeostasis (homeostasis). It happened tightly regulated by the body. Apoptotic pathway is divided into exogenous and endogenous two, the former by extracellular apoptotic signals such as tumor necrosis factor (tumor necrosis factor, TNF), Fas ligand (Fas ligand) and apoptosis of the cell surface receptor TNFR1 and Fas binds to both receptor trimerization, the trimeric the TNFR1 or Fas through the DD domain interactions own death domain structure (death domain, DD) and the adapter protein FADD in the cytoplasm raised the FADD, formed FasL-Fas-FADD or TNF-TNFR1-FADD death-inducing signaling complex (death-inducing signal complex, DISC). FADD DISC through its death effector domain (death effector domain, DED) and caspase-8 precursor DED interaction, raising the precursor of caspase-8, and the self-activation, and downstream caspase-3 activation, resulting in cell apoptosis. The endogenous apoptosis is due to ion irradiation, chemotherapy drugs, mitochondrial damage induced by the Bcl-2 family of pro-apoptotic factor cytochrome C (cytochrome C) released from the mitochondria into the cytosol, Apaf1, ATP / dATP combined into complex, known as apoptotic bodies (apoptosome) apoptosis in Apaf1 through the caspase raise domain (caspase recruitment domain, CARD) interacts with caspase -9 (caspase-9) precursors CARD , and thereby raise casepase-9 and self-activation of the activation of downstream caspases--3 (caspase-3), leading to cell apoptosis. Within the exogenous pathway from caspase-3 following exactly the same. Caspase-3 is a key protein regulating apoptosis, common for the exogenous pathway. Apoptosis, the cytoplasmic position caspase-3 enzymatic activation, executive function into the cell nucleus. This positioning changes the molecular mechanism is still unclear. The nuclear membrane of the nuclear pore complex (nuclear pore complex, NPC) is a transport channel between the nucleus and cytoplasm, macromolecules such as proteins and out of the nucleus requires nuclear localization signal (nuclear localization signal, NLS) and nuclear export signal (nuclear export signal , NES). Analysis of caspase-3 molecule contained in the NLS and NES can provide important clues for the understanding of the shift mechanism. We constructed a series of Caspase-3 shortening mutants and expression of GFP fusion was observed to locate them in the cells, the Identification of Caspase-3 in the molecule contained in the nuclear export signal NES (Nuclear Export Signal) and nuclear localization signal NLS (Nuclear Localization Signal). Found significantly the NLS Caspase-3 molecule does not exist, but there is a NES, the NES is located in the C-terminus of the small subunit of caspase-3, including 220 to 245 amino acid residues.
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