Intracellular Transport

Three mechanisms by which proteins are imported into organelles

1. nuclear pores via nuclear transport receptors

2. ER, Mitochondria, or peroxisome; use specific protein transporters

3. proteins leave ER using vesicles

Proteins using specific protein transporters much be in ... sequence and then refolded after they pass through

primary

Protein transporters

specialized receptor proteins on membrane surface

Mitochondrial transporter outer membrane (TOM) recognizes ... and ... to protein

signal sequence; binds

TOM diffuses cross the membrane until it locks in place with the ...

Transporter Inner Membrane (TIM0

What happens to the protein once TOM and TIM are aligned?

the protein is unfolded and threaded through the membrane

What happens once the protein is inside the mitochondria?

a peptidase cleaves the signal sequence and a chaperone protein refolds the protein

If a ER signaling sequence is recognized, the entire ribosome protein complex is transported to the ER via

Signal Eecognition Particle (SRP)

What allows the protein into enter from the ribosome into the ER

a protein translocator

Signal sequence halts protein from being further ...

translated

After being fed through a translocator protein...

protein production resumes

Coated vesicles

transport vesicles are encased with unique proteins; once its destination is reached the coating is released and vesicle fuses with target

Clathrin

protein that plays major role in the formation of coated vesicles

Adaptins

small proteins that connect clathrin to the vesicle

What does clathrin do once adaptins connect it to the vesicle?

it pulls on the receptors forming the vesicle

Dynamin

protein pinches off the neck of the vesicle separating it from the surrounding surface.

RAB Protein

identify the origin of the vesicle

Tethering proteins

present on target membrane, recognize an bind to RAB proteins, bringing the vesicle and target together.

T snare

target snare; proteins recognize and bind to V-snare (vesicle snare) proteins bringing vesicle and target into close contact

Before proteins leave the ER, they must undergo a ...

quality control process

What happens if chaperone proteins can't fold proteins properly?

the are degraded and recycled

Cystic fibrosis (CF)

affects cells that produce mucus, sweat, and digestive juices; it is thick and sticky instead of thin and slippery

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)

transmembrane chloride ion; regulates flow of Cl and water across the membranes

What causes Cystic fibrosis?

a defective or missing CFTR; mutated CFTR

Cystic fibrosis Dental implication

hypo salivation; thick, ropy saliva; swollen salivary glands; enamel defects; prone to infections

Vesicles enter the golgi via the

cis-face of the golgi

Vesicles exit the golgi via the

trans-face of the golgi

Constitutive Exocytosis Pathway

constant stream of cellular molecules from the golgi to the cell membrane

Regulated Exocytosis Pathway

molecules are shipped from golgi to membrane, but won't fuse with membrane until signal