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The nuclear envelope and traffic
Internal organization of the nucleusThe nucleolusThe nucleus during mitosis
The Nucleus
between the nucleus and cytoplasm
The Nuclear Envelope and the Traffic
Figure 8.1 The Nuclear Envelopenuclear pore complexes
Separation of the genome from the sites of mRNA translation thus plays a central role in eukaryotic gene expression.
functionally similar to
Figure 8.2 Electron Micrograph Showing Nuclear Pores
Figure 8.3 Electron Micrograph of the Nuclear Lamina
a meshwork of filaments underlying the inner nuclear membrane
Figure 8.4 Model of Lamin Assembly
60- to 80-kd fibrous proteinslamin A, B1, B2, C
coiled-coil
Prenylation of C-terminal Cyteine Residues
Figure 8.5 Molecular Traffic through Nuclear Pore Complexes
20 kd
9 nm
125000 kd50-100 proteins
Figure 8.6 Electron Micrograph of Nuclear Pore Complexes
eightfold symmetry organized around a large central channel.
Figure 8.7 Model of the Nuclear Pore Complex
from 9 nm to as large as 40 nm
Figure 8.8 Nuclear Localization Signals(NLS)
basic or classic NLS
Key Experiment 8.1 Identification of Nuclear Localization Signals
immunofluorescence mi´croscopy
Figure 8.9 Protein Import through the Nuclear Pore Complex
GEF: guanine nucleotide exchange factor
GAP: GTPase activating proteins
Table 8.1 Karyopherins with Known Substrates
Figure 8.10 Nuclear Export
Figure 8.11 a novel means of controlling gene expression
Figure 8.12 Transport of a Ribonucleoprotein Complex
RNP
Figure 8.13 Transport of snRNAs between Nucleus and Cytoplasm
Internal Organization of the Nucleus
Figure 8.14 Heterochromatin in Interphase Nuclei
euchromatin heterochromatins
constitutive heterochromatin facultative heterochromatin
Figure 8.15 Chromosome Organization
Figure 8.16 Organization of Drosophila Chromosomes
Figure 8.17 Organization of Chromosomes in the Mammalian Nucleus
Actively transcribed genes are adjacent to channel
heterochromatin
Fig.4.16 Structure of Metaphase Chromosomes
Figure 8.18 Looped Chromatin Domains
Figure 8.19 Clustered Sites of DNA Replication
BrdU labeled replication factories
20-50 nuclear speckles
Figure 8.20 Localization of Splicing Components
Figure 8.21 Cajal Bodies in the Nucleus
nulcear substructure: nuclear speckles, cajal bodies, PML bodies, nucleolus
nucleolus
The most prominent substructure within the nucleus
Figure 8.22 Ribosomal RNA Genes
1. a single transcription unit2. 200 copies vs. 2,000 copies of 5S rRNA genes3. ribosome production factory
Figure 8.23 Nucleoli in Amphibian Oocytes
1. Dividing cells needs 10 x 106 ribosomes2. thousands of nucleoli, which support the accumulation of nearly
1012 ribosomes per oocytes
Figure 8.24 Structure of the Nucleolus
the fibrillar centersthe dense fibrillar compnentsgranular component
Figure 8.25 Transcription of rRNA Genes
tandem arrays of rRNA geneshigh density of RNA polymerase Ithe knobs are formed by U3 small nucleolar RNP binding to the 5’-end of 45S pre-rRNA
Figure 8.26 Processing of Pre-rRNA
external transcribed spacerinteranl transcribed spacer U3 small nucleolar RNP
U8 snoRNAU22 snoRNA
Figure 8.27 Role of snoRNAs in Base Modification of Pre-rRNA
Figure 8.28 Ribosome Assembly
Figure 8.29 The Nucleus during Mitosis
spindle microtubules
chromosomes
Figure 8.30 Closed and Open Mitosis
Figure 8.31 Dissolution of the Nuclear Lamina
Figure 8.32 Breakdown of the Nuclear Membrane
Figure 8.33 Chromosome Condensation
SMC and condensin
structural maintenance of chromosomes
Figure 8.34 Re-Formation of the Nuclear Envelope
Molecular Medicine 8.2 Nuclear Lamina Diseases