Cell Bio Study Guide Part 1

Double membrane, perinuclear space, nuclear pore complex

What are the three core features of the nuclear envelope?

Outer and inner

What are the two membranes in the double membrane of the nuclear envelope?

Outer nuclear membrane

Nuclear membrane that is continuous with the rough ER and has ribosomes

Inner nuclear membrane

Nuclear membrane that contains specialized proteins that bind lamins and chromatin

Perinuclear space

The space that is present between two membranes

Nuclear pore complex

Large channels spanning both membranes that control movement in/out of nucleus

ER membrane, ER lumen

What is the outer membrane of the nuclear envelope for the ER? Space between membranes?

Membranes are continuous

What makes the perinuclear space form naturally?

Lamin binding proteins and chromatin binding proteins

What are the two proteins that the inner nuclear membrane contains?

Lamin binding protein

Protein in the inner nuclear membrane that anchors nuclear lamina

Chromatin binding protein

Protein in the inner nuclear membrane that organizes DNA

Ribosomes and cytoskeletal connectors

What two things does the outer nuclear membrane contain?

Nuclear lamina

Dense meshwork of intermediate filaments lining the inner nuclear membrane

Maintains nuclear shape, provides mechanical support, and anchors chromatin

What are the functions of the nuclear lamina?

A-type and B-type

What are the two types of lamins?

A-type lamin

Lamin found in differentiated cells that is more dynamic and not permanently membrane bound

B-type lamin

Lamin that is found in all cells and permanently associated with the membrane

Laminopathies

Diseases caused by mutations in lamins, especially lamin A

Weak nuclear envelope, abnormal nuclear shape, misregulated genes

What can laminopathies do to a nuclear envelope?

Provide mechanical strength, maintain nuclear shape, anchor chromatin

What do lamin filaments do?

Lamins and inner nuclear membrane proteins

What is the nuclear lamina made up of?

Structural support

What are lamins used for in the nuclear lamina?

Membrane proteins

Part of the nuclear lamina that is used to anchor lamins and chromatin and organize nuclear architecture

Under the inner nuclear membrane

Where does the nuclear lamina sit in the cell?

Prenylation

Addition of a lipid to a protein which makes the protein hydrophobic

Allows protein to anchor into membranes

Why is prenylation useful in a cell

B-type lamins

Which lamins are commonly prenylated to stay attached to the membrane?

Passive diffusion and active transport

What are the two main transport mechanisms for transport in the nuclear pore?

Small molecules pass with no energy or signal required

What happens in passive diffusion through the nuclear pore?

Large proteins and RNA pass with signal sequence, transport receptors, and energy

What happens in active diffusion through the nuclear pore?

Nuclear pore complex

Huge protein assembly embedded in the nuclear envelope

Cytoplasmic filaments, nuclear basket, central channel, and nucleoporins

What are the basic structural components of the nuclear pore complex?

Cytoplasmic filaments

Structural component of NPC, extends into cytoplasm and helps capture import cargo

Nuclear basket

Structural component of NPC, filaments on the nuclear side that help with export and quality control

Central channel

Structural component of NPC, main passageway through pore and selective barrier

Nucleoporins

Structural component of NPC, 30+ different proteins that build the entire pore structure

FG-NUP

Phenylalanine-glycine repeat nucleoporins, found inside central channel and form a selective, flexible barrier/filter

40S and 60S

What two subunits are ribosomes that are built in the nucleolus exported as?

Translation, cytoplasm

When do the 40S and 60S subunits join together? Where?