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Lecture 20: Membrane Protein Transporters
Terms in this set (52)
proteins that assist in the transport of glucose molecules across cell membranes
What method of transport do glucose transporters use?
Glucose transpoter is a Type ____ protein with ____ transmembrane helices.
What is the facilitated diffusion enzyme reaction equation?
v0= (Vmax + [S]out)/(Kt + [S]out)
What is the transport constant?
How many GLUT transporters are there?
GLUT1: tissue? Low/high Kt?
ubiquitous, low Kt, glucose uptake
GLUT2: tissue? Low/high Kt?
Liver, pancreatic islets, intestine
GLUT3: tissue? Low/high Kt?
brain, testis, low Kt, glucose uptake
GLUT4: tissue? Low/high Kt?
Muscle, fat, heart, low Kt, activity increased by insulin
Which GLUT is insulin dependent?
Tranporters that only carry one substance?
Two solutes using one protein - SAME direction
Two solutes using one protein - OPPOSITE direction
Simultaneous movement of two anions: HCO3- and Cl-
Chloride-bicarbonate (anion) exchanger - Antiporter
CO2 enters in the _______ and is remade and exited in the _______ in the Chloride-bicarbonate exchanger.
Respiring tissues; Lungs
What does active transport result in an accumulation of?
Solute above equilibrium point.
Energy transport for a chemical process equation
ΔG= ΔG* + RT ln([P]/[S])
for transport, ΔG* will =0
R= 8.315 J/mol*K
If we are moving down a concentration gradient, ΔG=
Simple transport with a charged solute equation:
ΔGt= RTln(C2/C1) + ZfΔy
Z= charge of species
When would Δy be negative?
pumping from outside to inside
What is the large family of cation transporters that are reversibly phosphorylated by ATP?
How are cation transporters reversibly phosphorylated?
ATPases are _________ proteins with _________ TM helices.
integral membrane; 8-10
ATPases are widespread, with ~______ in humans.
In one catalytic cycle, the Na+/K+ ATPase transporter transports
3 Na+ out
2 K+ in
1 ATP to ADP + Pi
The Na+K+ ATPase maintains low ____ and high ____ in cells.
The Na+K+ ATPase creates a net separation of charge, producing a resting membrane potential of __________ mV
-50mV to -70mV
The membrane potential from Na/K is essential for neurons in generating _______
What type of transporter pumps amino acids, peptides, proteins, metal ions, lipids, and drugs out of the cell against a concentration gradient?
_________ confers drug resistance to anti- tumor drugs.
What is an over-expression of MDR1 associated with?
treatment failure in cancers of the liver, kidney, and colon
What type of transporter uses transport down a gradient to provide energy for transport against a gradient?
Secondary Active Transport
What co-transporter is used in the intestines and kidney and what does it help transport?
Na+; glucose or amino acids (symporter)
What co-transporter is used in vertebrate cells and what does it help transport?
Na+; Ca2+ (antiporter)
In _______________, glucose and certain AAs are accumulated by symport with ______.
intestinal epithelial cells; Na+
2 Na+ move down its gradient to move _____ against its gradient.
Glucose moves down gradient through GLUT__ into ________.
Hydrophilic transmembrane channels for the passage of water.
Water secretion by _________ that produce sweat, saliva, and tears use aquaporins.
How do aquaporins play a role in kidneys?
water production and water retention
____ identical monomers each form a TM pore to pass a water molecule.
Structure of aquaporins prevents _______ through ________.
proton hopping; 2 Asn residues
Channels for rapid transport:
Ion channels have ___ identical subunits and a ________ filter.
What must happen to K+ before it can pass though ion chennel?
Protein domains that respond to a change in Vm.
Helices with ______ residues respond to membrane potential so that it can ________
Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.
acetylcholine receptors are an example of which channel?
How can Ach open a ligand gated channel?
by binding to receptor (AchR)
Once Ach binds to AchR, what can enter the cell?
Na+ an depolarizes postsynaptic cell
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