四川大学 细胞生物学10 细胞核.pdf

Chapter 10 Nucleus (细胞核) and Chromosome (染色体) Prof. Fangdong Zou College of Life Sciences, Sichuan University 1. The nucleus The nucleus is the cell’s information center. A mouse liver cell Double-membrane nuclear envelope Nuclear Pore complex (NPC) Nuclear Lamina (核纤层) Human Cell Nucleus of a cultured human cell Xenopus oocyte extracted with Triton X-100 •Provides mechanical support to the nuclear envelope •Serves as a site of attachment for chromatin fibers 2. The structure of nuclear pore complex NPC of an epithelial cell from a NPC of an amphibian oocyte rat kidney A model of a vertebrate nuclear pore complex Molecular mass: ~125 million 3. Nuclear transport through nuclear pore complex Free diffusion: ~9nm; ~5000 D (Fast); 17,000 D (2 min); 60,000 D (x) Active transport Active transport Injection of nonnuclear protein in cytosol ? ……………nucleoplasmin ………………. ? Selectivity: Nuclear localization signal (NLS) ？ NLS (from SV40 T antigen): -pro-lys-lys-lys-arg-lys-val- Normal pyruvate kinase: Chimeric pyruvate kinase in cytosol containing SV40 NLS: ? Importing proteins from the cytosol into the nucleus Bind to receptor Bind to Move through Interact with Receptor cytoplasmic pore Ran-GTP and back to filament dissociate cytosol The Ran GTPase: determining the direction of cargo molecule hnRNP proteins contain a nuclear-export signal (NES) References: •Cell, 1998, 92: 327 •Current Opinion in Cell Biology, 2006, 18: 299-306