Intracellular Transport Vocab

Cytosol

The main compartment of the cell where metabolic pathways and protein synthesis occur.

Nucleus

The site that contains the genome and is responsible for DNA and RNA synthesis.

Endoplasmic Reticulum (ER)

The site of protein and lipid synthesis, and the entry point for proteins destined for various cellular organelles.

Golgi apparatus

The compartment responsible for the modification and packaging of lipids and proteins.

Lysosomes

Organelles responsible for intracellular degradation.

Endosomes

Compartments involved in the sorting of endocytosed materials.

Mitochondria

Organelles that perform ATP synthesis via oxidative phosphorylation.

Chloroplasts

Organelles that handle ATP synthesis and carbon fixation through photosynthesis.

Peroxisomes

Organelles responsible for the oxidation of toxic molecules.

Endomembrane System

A system formed by the invagination of the plasma membrane including the ER, Golgi apparatus, peroxisomes, endosomes, and lysosomes.

Signal Sequence

A sequence of amino acids that directs a protein to its specific destination.

Nuclear Pore Complex

A large pore with water-filled channels in the nuclear envelope that allows diffusion of small molecules, water soluble and transport of macromolecules.

Nuclear Localization Signal

A specific signal that directs a newly synthesized protein from the cytosol into the nucleus.

Nuclear Import Receptors

Cytosolic proteins that recognize the nuclear localization signal and guide proteins to the nuclear pore by interacting with the fibrils extending from the pore

Ran-GAP (GTPase Activating Protein)

A cytosolic protein that triggers GTP hydrolysis in the Ran GTPase cycle.

Ran-GEF (Guanine Nucleotide Exchange Factor)

An accessory protein that promotes the exchange of GDP for GTP in the nucleus during nuclear transport.

Signal Recognition Particle (SRP)

A particle that binds to the ribosome and the ER signal sequence, slowing down translation.

Protein Translocator

A channel in the ER membrane through which proteins are threaded.

Signal Peptidase

An enzyme that cleaves the ER signal sequence off a soluble protein in the ER lumen.

Stop-Transfer Sequence

A hydrophobic sequence that halts translocation and retains a protein in the lipid bilayer.

Start-Transfer Sequence

An internal hydrophobic signal sequence that anchors a multiple-pass transmembrane protein.

Transport Vesicles

Vesicles that carry soluble proteins and membrane components between the endomembrane system and plasma membrane.

Coated Vesicles

Vesicles that bud from membranes with a protein coat that helps shape the membrane and capture cargo.

Adaptins

Proteins that capture specific cargo molecules and help secure the clathrin coat to the vesicle membrane.

Dynamin

A GTP-binding protein that assembles around the neck of a budding vesicle to pinch it off from the membrane.

v-SNAREs and t-SNAREs

Complementary receptors found on the transport vesicle and target membrane that facilitate fusion of lipid bilayers.