Membrane Transport Flashcards
What’s partition coefficient
Kow: constant for partitioning octanol and water
4 types of gated ion channels
- Voltage
- Ligand gated (extracellular ligand)
- Ligand gated (intracellular ligand)
- Mechanically gated
Relationship between Km and affinity
Lower Km, increased affinity
Glut 1 location and features
Ubiquitous, abundant in RBC, Low in skeletal muscle
High affinity
Glut 2 location and features
Low affinity to allow regulation of glucose levels
In hepatocytes and pancreatic beta cells
Glut 3 location and features
High affinity
In neurons
Glut 4 location and features
Adipocytes and muscle
Insulin recruits GLUT4 to CM
3 examples of primary AT
Na+/K+ ATPase in PM
H+ ATPase in lysosomal membrane
Ca2+ ATPase in PM and sarcoplasmic reticulum of muscle
Na+/K+ ATPase
3 Na+ binds to intracellular site -> auto phosphorylation-> change in shape, pump opens to outside-> Na+ released-> 2K+ bind-> dephosphorylation, pump opens to inside again
Which drug obstructs Na+/K+ pump? How does it help patients with congestive heart failure
Ouabain binds to K+ sites-> [na+] intracellular increases-> na+/ca2+ antiporter antiporter inhibited-> intracellular [ca2+] increases-> triggers cardiac muscle contraction
Secondary AT example and location
SGLUT 1 (sodium glucose transporter)
Intestinal epithelial cells
Proximal tubules in kidneys
Na+/glucose cotransporter and cholera treatment
Vibrio cholerae-> overactivates gs alpha (g protein subunit)-> adenylyl cyclase produces cAMP-> increases CFTR activity (chloride channel)-> increased cl- secretion -> huge electrolyte and fluidity loss
Treat,ent includes a high concentration of glucose which drives Na+ back into cells through Na+/glucose cotransporter-> water and cl- consequently get reabsorbed
