BIOL 1090 Lecture Notes - Lecture 22: Nuclear Lamina, Nuclear Membrane, Nuclear Pore
16 Dec 2017
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March 29, 2017 - L22: The Nucleus
Characteristics
•5-10% of cell volume
•Ca. 10 um diameter
•Typically one/cell
Functions
•Storage, replication and repair of genetic material
•Expression of genetic material
•Ribosome biosynthesis
Structure
•Nuclear envelope
oNuclear membrane
oNuclear lamina
oNuclear pores
•Nuclear content
oChromatin (DNA + protein)
oNucleoplasm
oNuclear matrix
onucleolus
Nuclear envelope
•2 parallel phospholipid bilayers
oOuter membrane: binds ribosomes
and is continuous w/rough ER (RER)
oInner membrane: contains integral
membrane proteins that connect to
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nuclear lamina
oMembranes are separated by 10-50nm
oIntermembrane space continuous w/ER lumen
•Separates nuclear content from cytoplasm
oSeparates transcription and translation
•Selective barrier
oAllows limited movement of molecules b/w nucleus and cytoplasm
•Binds nuclear lamina
Nuclear lamina
•Mutations in a lamin gene (LMNA) implicated in Hutchinson-Gilford Progeria Syndrome,
a rare disease that causes premature aging in children
oDestabilizes Lamin A nuclear envelope
oRare disease causing premature aging in children
oQuickly acquire wrinkles, lose hair and suffer damage to their arteries
oResults in death during adolescence
Structure
•Thin meshwork of filaments
oLamins (type of intermediate filament)
oApprox. 10 nm diameter
oIntegrity regulated by phosphorylation
•Bound to inner surface of Nuclear Envelope (NE)
oVia prenyl group linked to lamin polypeptide
oVia integral membrane proteins
Functions
•Support structure for NE
•Attachment sites for chromatin
Nuclear Pores
•Nuclear function is dependent upon protein import
oStructural proteins
▪Nuclear lamins and matrix
▪DNA packaging
oDNA replication
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Document Summary
Structure: nuclear envelope, nuclear membrane, nuclear lamina, nuclear pores, nuclear content, chromatin (dna + protein, nucleoplasm, nuclear matrix, nucleolus. 2 parallel phospholipid bilayers: outer membrane: binds ribosomes and is continuous w/rough er (rer, inner membrane: contains integral membrane proteins that connect to nuclear lamina, membranes are separated by 10-50nm, intermembrane space continuous w/er lumen. Separates nuclear content from cytoplasm: separates transcription and translation. Selective barrier: allows limited movement of molecules b/w nucleus and cytoplasm. Thin meshwork of filaments: lamins (type of intermediate filament, approx. 10 nm diameter: integrity regulated by phosphorylation. Bound to inner surface of nuclear envelope (ne: via prenyl group linked to lamin polypeptide, via integral membrane proteins. Support structure for ne: attachment sites for chromatin. Nuclear pores: nuclear function is dependent upon protein import, structural proteins, nuclear lamins and matrix, dna packaging, dna replication, dna repair, transcription, rna processing and export, ribosome synthesis and export. Inner and outer membranes of ne fuse at pores: approx.
