examples of transporters/channels - exam 1

What is the Glucose 1 Transporter an example of?

uniport

What are aquaporins?

channels that allows transport of small amount of water molecules

• abundant in cells that must transport at a high rate, epithelial cells of the kidney

What are AChRs?

transmitter gated (ligand gated) ion channels found on postsynaptic skeletal muscle cells or postsynaptic neurons

• opening transiently in response to acetylcholine

• two main types are nicotinic choline receptors (nAChRs) and muscarinic acetylcholine receptors (mAChRs)

What is nicotinic acetylcholine receptors (nAChRs)?

• ligand-gated ion channels that activated by acetylcholine or nicotine 

• found in CNS and PNS

• CNS - synapses between neurons, where they mediate between excitatory neurotransmission

• PNS - at neuromuscular junctions and mediate the signals from motor neurons to skeletal muscle

What is the GABA receptor?

ligand gated ion channel that is regulated by GABA

• when GABA binds to receptors → influx of chloride ions (Cl-) into postsynaptic neuron

• neuron becomes less likely to fire an action potential

• disruption of GABA can lead to various neurological disorders such as epilepsy, anxiety disorders, and schizophrenia

What are the sodium potassium (Na+/K+) pump and a type of calcium (Ca2+) pump examples of?

P type ATP driven pumps

• phosphorylate themselves during the pumping cycle

What is MDR (multi drug resistance) an example of? — also called P glycoprotein

ABC transporter (ATP binding cassette transporters)

• different structure than the P type and mostly pump small organic molecules

What is the name for a P type calcium pump?

SERCA (sarcoplasmic/endoplasmic reticulum calcium ATPase)

What is CFTR (cystic fibrosis transmembrane conductance regulator protein) an example of?

atypical ABC transporter 

• functions more like a channel than a carrier

Various symporters such as the Sodium Glucose Co-transporter (SGLT) make use of what electrochemical gradient?

the one set up by the Na+/K+ pump

What is SERT (serotonin transporter)?

Na+ dependent neurotransmitter transporter (reuptake transporter)

• located on presynaptic neurons in the CNS

What kind of transporters are found in gut epithelial cells?

Na+ linked symporters

• at the apical (absorptive) part of the plasma membrane

• transports nutrients into the cell

uniporters

• at the basolateral part of the membrane

• allow nutrients to leave the cell down their concentration gradients (passive) and to enter the bloodstream for distribution throughout the body