Intracellular Transport (Chapter 10)

These flashcards cover essential vocabulary and concepts related to intracellular transport, including cell types, transport mechanisms, and protein processing pathways.

Eukaryotic Cells

Cells distinguished by membrane-bound organelles and complex intracellular organization.

Endomembrane System

A network of connected organelles involved in protein and lipid processing and transport.

Components of the Endomembrane System

Major components include the ER, Golgi apparatus, lysosomes, endosomes, and peroxisomes.

Signal Sequence

The feature that determines the final destination of a protein inside the cell.

Nuclear Localization Signal (NLS)

A short amino acid sequence that directs proteins to the nucleus.

Cytosol

The location where proteins lacking targeting signals remain.

ER Signal Sequence

An attachment that directs a cytosolic protein into the ER.

Nuclear Pore Complex (NPC)

The structure that controls transport into and out of the nucleus.

Selective NPC

The characteristic of allowing specific macromolecules to pass while blocking others.

Folded Proteins

Yes, proteins can enter the nucleus in their folded form.

GTP Hydrolysis

The energy source that powers nuclear transport.

Ran GTPase

The molecular switch that regulates nuclear import and export.

Ran-GTP Abundance

Most abundant in the nucleus.

Ran-GDP Abundance

Most abundant in the cytosol.

Ran Gradient

Important for providing directionality to nuclear transport.

Protein Synthesis Location

Most proteins are synthesized in the cytosol before targeting.

Protein Unfolding

Many proteins must unfold before crossing a membrane.

Protein Translocators

Structures that allow proteins to cross membranes.

ER Entry Point

The reason the ER is the entry point of the secretory pathway.

Signal Recognition Particle (SRP)

The particle that recognizes ER signal sequences during translation.

SRP Binding Effect

SRP binding temporarily pauses translation.

Soluble vs Membrane Proteins

Soluble proteins are released into the lumen; membrane proteins remain embedded.

Hydrophobic Stop-Transfer Sequence

The sequence that anchors proteins in the membrane.

Vesicular Transport

Used for moving proteins and lipids between membrane-bound compartments.

Secretory Pathway

The pathway for outward transport from the ER to the cell surface.

Endocytic Pathway

The inward transport from plasma membrane to endosomes and lysosomes.

Coat Proteins Role

They shape membranes into vesicles and select cargo.

Vesicle Coat Types

Major types include clathrin-coated and COP-coated vesicles.

Clathrin

The protein that forms a lattice around budding vesicles.

Adaptins

Proteins that link cargo to clathrin.

Dynamin

The protein that pinches off budding vesicles from membranes.

SNARE Proteins

Proteins that mediate vesicle docking and fusion.

v-SNAREs

Located in the vesicle membrane.

t-SNAREs

Located in the target membrane.

SNARE Binding Result

When v-SNAREs bind t-SNAREs, membranes are pulled together until fusion occurs.

Vesicle Fusion Result

Results in cargo delivery to the target compartment.