Cell II Flashcards
Proteins constitute how much mass of the membrane?
25-75%
How do you remove peripheral proteins from the membrane?
salt solutions
Abnormal cleavage of beta-APP form what?
A-beta peptides that aggregate as amyloid fibrils. This is Alzheimer’s disease
The precursor to the prion protein in Creutzfeldt-Jakob disease is found where in the cell? What conformation is it in?
GPI anchored to the cell membrane within lipid raft
Alpha helix
What does the prion protein in Creutzfeldt-Jakob disease turn into?
Beta-pleated sheets, and amyloid fibrils
What does the cerebrum of a patient with cruetfeld jakob disease look like
Spongiform (Swiss cheese)
What substance will identify the amyloid plaques in Alzheimer’s and cruetzfeld jakob disease?
Congo red
What type of protein is the beta-amyloid protein? What are its functional attributes?
Intergral (transmembrane) protein
neuronal migration during development, synapse formation/repair
What are the functions of membrane proteins? (6)
Receptors Pumps Channels Linker proteins Structural proteins (ECM) Enzymes
What is the medical relevance of receptors?
Pharmacological agents may act as agonists or antagonists
How do receptors regulate their response?
[C] of receptors
What is the clinical significance of estrogen receptors?
target for CA (tamoxifen)
What is the function of Na/K transporters? Are the energy dependent?
Moves 3 Na ions out of the cell and exchanges 2 K ions.
This can regulate cell volume
ATP driven
Digoxin is used in the treatment of heart failure, and inhibits Na/K pumps. This leads to an increase in intracellular [Na]. What is the purpose of doing this?
Since Ca is exchanged for Na in its pump, the Ca pump will also slow down, increasing sacroplasmic [Ca]
What type of transporter is GLUT5?
Secondary active synporter with Na
Where is the Na/K pump that is used in transporting glucose?
On the interface of the intestinal epithelial cell, and the extra cellular fluid
(NOT on the intestinal lumen side with the Glu transporter)
Where is MDR-1 expressed? (4) In what disease can it be a problem?
kidney, intestine, liver, and blood brain barrier
Will pump out antineoplastic agents if overexpressed in CA cells
What is the function of MDR-2?
Transports bilirubin
What is the function of MDR-3?
Expressed in liver where it functions as a flipase of phosphatidylcholine so that is may be excreted into bile
What is Dubin-Johnson syndrome?
Defective MDR-2 transporter, leading to the accumulation of bilirubin
How do you overcome MDR-1 overexpression in CA cells
RNA interference (silence the gene for MDR-1 by eliminate its RNA)
How many isoforms of Aquaporin are there?
12
How is aquaporin 2 induced in kidney cells?
Vasopressin or ADH (its receptor), causes translocation of aquaporin receptors to the plasma membrane of collecting tubule, increasing water re-absorption
What disease involves defective aquaporins in the kidney?
Nephrogenic Diabetes insipidus
How does EtOH affect ADH receptor?
Inhibits it
What ion is symported with Cl in CFTR channels?
Na
Why do cystic fibrosis patients taste salty?
Dysfunctional Cl transport = build up of Na/Cl on skin
Why do cystic fibrosis patients have thick mucus secretions?
Lack of export of Cl causes increase of [Cl]. Na and H20 transported back into the cell for balance.
What other areas are obstructed in cystic fibrosis?
bile duct, intestines, ductus deferens
Where is lactase found?
On the cell wall of intestinal epithelium
Duchenne’s muscular dystrophy is the result of a defect in what protein?
Dystrophin
What is the function of Dystrophin?
Links to dystroglycans that are in the plasma membrane, which in turn link to ECM proteins
Where are glycolipids found?
The extracellular side of the plasma membrane
What is the receptor for the cholera toxin (hint” it’s a glyolipid)
Gm1 ganglioside
What is the effect of cholera toxin?
Ramps up adenylate cyclase activity to increase CFTR transporters to push out H2O
What is the function of glycolipids on RBCs?
Have negative charges to keep RBCs apart
What are the roles of glycolipids/proteins?
Protection
cell-cell adhesion
signalling
What are the four processes of vesicular transport across the membrane
- Endocytosis
- Exocytosis
- Porocytosis
- Exosomes
How many different pathways are there for endocytosis? What is needed?
5
ATP and Ca
Where does macropinocytosis take place?
thyroid cells taking up thryoglobulin
Dendritic cells for immune surveillance
What is the type of molecule needed for macropinocytosis?
Actin
How specific is macropinocytosis?
Not at all
What is the normal function of beta-amyloid precursor protein (5)?
neuronal migration during development, synaptic formation/repair, cell signalling, long-term potentiation of memory, cell adhesion
What is the function of the normal prion protein found in creutzfeldt-Jakob disease (3)?
- may be neuroprotective against ischemia
- control circadian rhythms
- may serve serve to organize the myelin sheath
Kuru disease stained with congo red will show what? PAS?
Large red amyloid aggregations with congo, black dots with PAS
Water follows what ion? How can the cell manipulate this to regulate the water content of the cytoplasm?
Na
Na/K pump can shift Na out of cell, to lose water
What is the effect of increased Ca in cardiac muscle?
Increased contractile force
In the glucose/Na pump, where does Na travel (starting from the intestinal lumen)?
symport with Glucose down [C] gradient, and is pumped into the ECF by Na/K pump.
What technique would you use to identify Duchenne’s muscluar dystrophy?
Immunocytochemistry
