Flashcards in Lecture 5 Deck (43):
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
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
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?
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
- 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?
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
- 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
-protein used to patch up microperforations in membranes of muscles cells
-sent out by golgi in response to perforations
-mutation in dysferin causes muscular dystrophy and myopathy
How does the Golgi function in insulin processing?
1) prepro insulin made in rER and sent to golgi
2) golgi converts it to preinsulin and packages it to be shipped out with an enzyme that cleaves off the pro to give mature insulin
-caused by a mutation in proinsulin that causes it to be packaged into a constitutive (continuous) secretory pathway which causes excessive excretion of proinsulin
-The enzymes that are meant to cleave proinsulin and make it into insulin are still good and go down the regulated PW.
-both not together so no insulin
Cis face of golgi
faces the side with the incoming proteins from the rER
trans face of golgi
faces where proteins are packaged and ready for secretion
- membrane limited compartments
-organelles that sorti and identify molecules for recycling and degradation in lysosomes
What are the four classically defined endosomal compartments
and in general how do they differ?
-> they differ by having unique locations in the cytoplasm, different luminal pH, and having different molecular markers
what's responsible for acidifying the internal environment of endosomes?
what's the pH of recycling and early endosomes? How does that compare to the cytosol?
6.2-6.5, slightly more acidic than cytosol
where are early and recycling endosomes located?
at the cells periphery
What do recycling endosomes do?
recycle endosomes and glucose transport in response to insulin
What do multivesicular bodies do, where are they located and what pH do they possess?
-they receive material from early endosomes and fuse with late endosomes to hand that material off
-located between early and late endosomes
why are multivesicular bodies called so?
because they contains lots of membranes and vessicles (from early endosomes that migrate there)
What is the pH of late endosomes? where are the late endosomes located?
5.0, located near the Golgi and nucleus
what do late endosomes do?
they dispose of their material (vesicles, membrane) by either fusing with lysosomes or becoming lysosomes (highest pH)
where do most exosome like bodies come from?
How do recycling endosomes work in terms of insulin?
- when insulin has not binded to it's receptor on the cell surface, the recycling endosome holds the glucose transporter inside the cell
-when insulin binds the receptor, it sends a signal to the recycling endosome which then sends glucose transporter up to the surface of the cell to allow for greater uptake of glucose into the cell
-if prob with signal, no glucose transporter is sent to the surface of the cell
what are the four fates of receptor-ligand complexes that have been endocytosed by endosomes?
1) the ligand is released intracellularly and the receptor is recycled (LDL)
2) Both ligand and receptor are recycled and sent back outta the cell (iron and it's transporter)
3) Ligand and receptor are transported across the cell and secreted via transocytosis (glandular cells (IGA) and antibodies)
4) Both ligand and receptor are degraded (FGFR3- prob= achondroplasia)