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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?

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


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



-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?

-early endosomes
-recycling endosomes
-multivesicular bodies
-late endosomes
-> 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?

H+ ATPases


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
-pH= 5.0-6.2


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?

multivesicular bodies


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)


How does Achondroplasia arise?

-Fibroblast growth factor and it's receptor are supposed to be used and then degraded via lysosomes
-in achondroplasia, theres a mutation in FGFR that prevents lysosomes from targeting it for degradation and instead it goes into the plasmalemma and is amplified causing dwarfism