Lecture 20 Flashcards
Once a protein is targeted into the ER lumen, fully synthesized and properly folded, what is its 2 options of sorting
(biosynthetic/secretory pathway)
Option 1: it is retained in the ER lumen if it functions there
Option 2: it is transported from the ER to the Golgi complex for further modification and delivered to other distal parts of the pathway
What direction is it when material moves from the ER to the Golgi and then to other compartments and the plasma membrane
Proximal to distal direction
What part of the Golgi complex is at the proximal end, which part is at the distal end?
Proximal: cis-Golgi network (CGN)
Distal: trans-Golgi network (TGN)
Describe the structure of the Golgi complex
Smooth, flattened cisterna
8 or fewer cisternae/stacks (a few to several 1000 stacks per cel)
curved like a shallow bowl
Shows polarity: cis-medial-trans cisternae (all contain different enzymes and have different functions)
Cisternae are biochemically unique
membrane supported by protein skeleton (actin, spectrin)
Scaffold linked to motor proteins (for movement of vesicles)
What is the function of the cis-Golgi network (CGN)
Acts as a shorting station (decides if proteins should move into another Golgi station or if it goes back to the ER)
What is the function of the trans-Golgi network (TGN)
shorts proteins into different types of vesicles (vesicles got to plasma membrane or other intracellular destinations)
What is another function of the Golgi complex
processing plant of the cell
synthesizes polysaccharides and specific modifications of proteins and lipids
How are proteins modified in the Golgi? Where do fully processed proteins end up?
Proteins get modified step-wise and they travel through the Golgi
Fully processed proteins are found in the TGN
What can be used to observe biochemical differences in Golgi cisternae
differential staining
(specific dye used to identify)
Do fully processed proteins just stay in the TGN?
No, they get delivered to their final destinations (Where they function?)
What are some examples of different pathways in exocytosis
Mucin secretion (constitutive secretory pathway)
Release of insulin and neurotransmitters (regulated secretory pathway)
What is the function of the goblet cell in the GI tract
It produces protective mucus that contains glycoprotein mucin
What type of mutation is responsible for cystic fibrosis
mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR)
deletion of three nucleotides that result in the loss of the amino acid phenylalanine
What are the 2 functions of coat proteins
1) helps to form the vesicle
2) help to select “cargo” (material inside or on the vesicle)
What are COPI and COPII and where do they assemble
they are protein complexes
Assemble on cytosolic surface of donor compartment membranes where budding takes place
