C Nuclear pore complex (NPC) NUCLEOPLASM Inner membrane Nuclear of nuclear envelope pore complex 120nm一 Basket of fibers Anchor Nuclear protein lamina Ri Nuclear Ring Cytoplasmic Ring membrane Transporter of nuclear envelope Fibe EndoplasmIc reticulum Ribosomes CYTOSOL
C. Nuclear pore complex (NPC) Cytoplasmic Ring Nuclear Ring
D. Molecules enter and exit the nucleus through nuclear pore complex RN Chromosomal replication DNA mRNA tRNA Ribosomal NUCLEUS Proteins needed Proteins needed for chromosome prote Protein syn wing CYTOPLASM Completed protein Bidirectional traffic
D. Molecules enter and exit the nucleus through nuclear pore complex Bidirectional traffic
o Passive transport--passively diffuse >3000-4000 NPC/cell (mammalian); To import about 106 histone/3 mins. (DNA-Sythesizing cell)=100 histone/ min/NPC >Each NPC contains one or more open aqueous channels:9 nm in diameter and 15 nm long The effective size of these channels has been determined by injecting various sizes of colloidal gold particles and examined by electron microscopy. <10 nm in diameter able to enter the nucleus <60kd globular protein
❖ Passive transport—passively diffuse ➢3000-4000 NPC/cell(mammalian); To import about 106 histone/3 mins.(DNA-sythesizing cell) = 100 histone/ min/NPC ➢Each NPC contains one or more open aqueous channels: 9 nm in diameter and 15 nm long ➢The effective size of these channels has been determined by injecting various sizes of colloidal gold particles and examined by electron microscopy. <10 nm in diameter <60kd globular protein Able to enter the nucleus
☆ Active transport limited proteolysis radioactive radioactive radioactive colloidal gold particle nucleoplasmin coated with tails MICROINJECTION INTO CYTOSOL OF XENOPUS OOCYTE 0)(a(8 nucleus. INCUBATION DETECTION BY AUTORADIOGRAPHY DETECTION BY EM UPTAKE INTO UPTAKE INTO NUCLEUS UPTAKE NOCLEUS UPTAKE INTO NUCLEUS > Transport of large proteins into nucleus needs nuclear localization signal (NLs)
❖ Active transport ➢Transport of large proteins into nucleus needs nuclear localization signal (NLS)
NLS are present only in nuclear proteins A typical NLs contains several consecutive basic amino acids (the positively charged Aa: Lys, Arg) Normal pyruvate kinase: Chimeric pyruvate kinase in cytosol containing sv40 Nls: in nucleus
➢ NLS are present only in nuclear proteins A typical NLS contains several consecutive basic amino acids (the positively charged Aa: Lys, Arg) Normal pyruvate kinase: in cytosol Chimeric pyruvate kinase containing SV40 NLS: in nucleus