Membrane transport Flashcards
Types of gating
- Ligand-gated
- Voltage-gated
- Mechanically-gated
TRUE OR FALSE
Passive transporters can be symport
FALSE
They are only function as uniport through an ‘alternative access mechanism’.
Properties
Passive transporters
- Highly selective
- Slow
- Saturable (reaches Vmax)
- Molecule must BIND to the binding site.
What is the mechanism that passive transporters use?
Alternating access mechanism
TRUE OR FALSE
Primary active transporters are channels
FALSE
They are pumps!
P-type transporter mechanism
- ATP hydrolysis.
- Results in ADP + Pi
- The protein pump is phosphorylated causing a conformational change
P-type transporter examples
- NA+ , k+ -ATPase (antiport)
- Ca2+ - ATPase (uniport) [->out of the cell]
- H+ ,K+ -ATPase (antiport)
What do P-type transporters transport?
Cations
(e.g. H+, K+, Na+, Ca+)
Where are V-type transporters
Found in vesicles (ergo are intracellular)
V-type transporters
- Primary active transporter
- found in vesicles
- Pump H+ into organelles
- Function via ATP hydrolysis
F-type transport
- Primary AT
- found in inner mitochondrial membrane
- Pump H+
- Funcion via ATP synthesis
F-type transporter mechanism
The movement of H+ down its gradient causes the ATP synthesis.
Creates energy
ABC transporters
- Primary active transporter
- All ABC transporters are dimers
- Requires two ATP molecules
Dimer
A molecular complex consisting of TWO proteins.
In molecular transport, dimers are PROTEIN PUMPS that consist of two proteins not one.
ABC transporter mechanism
- Two molecules of ATP bind to the dimer causing conformational change.
2 . Molecule diffuses into the otherside.
3 . ATP are hydrolysed, the pump goes back into its original conformation.
However, the pump is NOT PHOSPHORYLATED! at any point.
Coupled transport
When the movement of a proton or sodium down its gradient can supply enough energy to allow another molecule travel AGAINST its conc. gradient
TRUE OR FALSE
Ion channels are integral membrane proteins
TRUE
What ion channel or transporter does Dapaglifozin act at and what is it used to treat?
Dapaglofozin inhibits the Na+ - glucose co-transporter in the kidneys.
This reduces the amount of glucose reabsorbed in the kidneys and therefore lowers blood glucose.
Used in the treatment for Type 2 diabetes.
What ion channel or transporter does Digoxin act at and what is it used to treat?
Digozin inhibits the sodium-potassium ATPase in the heart. This results in an increase of Sodium in the heart which will drive an influx of calcium in the heart and increase contractility.
Used in the treatment for heart failure and certain arrhythmias.
What ion channel or transporter does Fluoxetine act at and what is it used to treat?
An SSR inhibitor that blocks the reuptake of serotonin, increasing its availability in the synapses.
Used in the treatment for depression and anxiety disorders.
What ion channel or transporter does Lidocaine act at and what is it used to treat?
Lidocaine blocks voltage-gated sodium channels , preventing nerve cell depolarisation and inhibiting the conduction of pain signals.
It can also stabilise heart rhythmby blocking abnormal electrical activity in cardiac cells.
Used in local anesthesia and to treat arrhythmias.
What ion channel or transporter does Omeprazole act at and what is it used to treat?
Omeprazole acts as a proton pump inhibitor by inhibiting the H+/K+ ATPase in the parietal cells of the stomach.
Reduces the secretion of gastric acid.
Used to treat: Peptic ulcers,Gastroesophageal reflux disease and more
