nuclear envelope
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Transcript of nuclear envelope
THE NUCLEAR ENVELOPE,
NUCLEAR LAMINA & PORE COMPLEX
TOPICS TO COVER:Nuclear envelope:
Nuclear membranes – inner & outer membranes.
Nuclear lamina Nuclear pore complexes
– structure – function
NUCLEAR ENVELOPE
Nuclear envelope : consists of two nuclear membranes that envelops the nucleus of an eukaryotic cell, an underlying nuclear lamina, and nuclear pore complexes.
Encloses nuclear DNA. Defines the nuclear compartment. Separates nucleus and cytoplasmic contents separate
metabolic compartments. Structural framework for nucleus.
TOPICS TO COVER:Nuclear envelope:
Nuclear membranes – inner & outer membranes.
Nuclear lamina Nuclear pore complexes
– structure – function
NUCLEAR MEMBRANES:2 lipid bilayer membranes: •Punctured nuclear pores connect the two membranes. •Different in protein composition•Separated by perinuclear space
Inner membrane – associated with nuclear lamina Outer membrane – continuous with endoplasmic reticulum
NUCLEAR MEMBRANES:
TOPICS TO COVER:Nuclear envelope:
Nuclear membranes – inner & outer membranes.
Nuclear lamina Nuclear pore complexes
– structure – function
NUCLEAR LAMINA•Intermediate filaments & membrane associated proteins(Lamins & nuclear lamin-associated membrane proteins)•Lamin types: A, B1, B2, & C•Mechanical support•Regulates cellular events
TOPICS TO COVER:Nuclear envelope:
Nuclear membranes – inner & outer membranes.
Nuclear lamina Nuclear pore complexes
– structure – function
STRUCTURE OF THE NUCLEAR PORES:
•Large compared to other proteins.•Octagonal symmetry.•Mass approx. 125 megaDaltons in vertebrates.•Cytoplasmic fibrils (tentacle-like)•Nuclear meshwork
STRUCTURE OF NUCLEAR PORE
STRUCTURE OF NUCLEAR PORE
FUNCTION OF NUCLEAR PORE
FUNCTION OF THE NUCLEAR PORE
Passive diffusion of low molecular weight solutes
Regulated transport of macromolecules larger than 40 kDa
Nuclear import signal: NLS Nuclear export sequence: NES Importins: cytoplasm to nucleoplasm Exportins: nucleoplasm to cytoplasm GTPase Ran controls interactions of cargo
and karyopherin