Lecture 5 Flashcards
(43 cards)
what makes phospholipids and where?
sER and rER in the cytosolic (inside part of the cell) lipid monolayer
what are phospholipid translocators?
membrane bound enzymes that catalyze the flip flop of phospholipids from one monolayer to the other (from cytosolic side to lumen side)
-without this, new lipid bilayers could not be formed
what’s the phospholipid exchange mechanism?
it’s the mechanism/protein that allows for transport of new phospholipids to other organelles’ membranes besides the ER
Atlastin
GTPase
protein involved in constructing ER
what happens with abundance and deficiency of Atlastin?
Abundance- increased ER membrane fusion and normal golgi is absent
deficiency- fragmentation of ER -herediary spastic (because ca) paraplegia
Hereditary spastic paraplegia
leg stiffness, gait probs, stumbling dues to difficulty with hip flexion and dorciflexion of foot, retardation
caused by low Atlastin (makes ER)
what can too much ca intracellularly do to a cell?
- damage membrane
- damage mitochondria leading to decreased ATP
- damage to nuclear component of cell
Proteosomes
large ATP-dependent protease
located in the nucleus and cytoplasm
What do proteases break down?
1) cell cycle regulating proteins
2) malformed, denatured, damaged proteins
3) antigenic proteins
what percentage of newly formed proteins are broken down by proteosomes because they are deficient?
30 percent
what happens to antigenic proteins once they are broken down by proteosomes?
they are presented to t cells that initiate an immune response
What two kinds of proteosomes are there?
1) ubiquitin mediated- directs
2) non ubiquitin mediated
what’s thought to inhibit proteosomes?
1) prion proteins
2) alzheimers plaques
how does parkinson’s disease relate to proteosomes?
Parkinson’s caused by defective ubiquitination of proteins that flag the proteins for degradation by proteosomes
How are cystic fibrosis and proteosomes related?
one form of CF caused by proteosomal degradation of a CFTR ABC cl channel that is slow to form but competent
Multiple myloma and proteosomes?
if you inhibit proteosomes, you can help to decrease the degradation of pro-apoptotic factors that get rid of cancer cells
drug-bortezomib
Golgi apparatus
- major storing and distribution center of proteins
- packages proteins into vesicles to be shipped out to other parts of the cell
how are proteins stored in golgi?
based on a.a. sequence and carbohydrate moities
How does the Golgi alter proteins?
1) glycosylation
2) sulfation
3) phosphorylation
4) adding of oligosaccarides (carbs) done in rER but trimmed in golgi
5) proteolytic cleavage
anatomy of the golgi
3-10 sacks called cisternae that form the little flaps
state what the movement of proteins thru the cell looks like thru the cell
rER to golgi to condensing vesicles to zymogens
How is copper dealt with in the hepatic cell?
1) it is packaged into vesicles with the ATP7 receptor and sent out thru the bile
2) golgi in the hepatocyte has ATP7 receptor that brings copper into the golgi and attaches a protein called ceruloplasm to make ceruplasmin in the golgi and sends the ceruloplasmin out to be excreted thru the bloodstream
wilson’s disease
- mutation in protein pump for the receptor for copper in the golgi of liver cells
- causes impaired secretion of copper and kaser-fleicher rings (copper deposits) in eyes and neuro probs
- decrease in cerulosplasmin because not getting copper into the golgi
Negative golgi image
a pale staining area of cytoplasm seen in H and E staining
- it is NEITHER acidophilic or basophilic
- no ribosomes so pale