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