Membrane Transport Flashcards
4 Major Classes of Membrane Lipids:
- Phosphoglycerides: derived from _ carbon ___ backbone; _ FA chains attached to backbone; _ major types.
- 1 FA is usually _____, leading to ____, which increases _____.
- Head group consists of ___, ____, then ___ group.
- PTE an PC enriched in _____ membranes - Sphingolipids: derived from _____ backbone; ____ is major one.
- can contribute to formation of ___ ____ alongside cholesterol - Glycolipids: often ______ backbone; _____ always on ____ face.
- enriched in _____
- Example: ____ ganglioside used for entry of _____. - Sterols: primarily ____
- contains _____, _____, and _____
4 Major Classes of Membrane Lipids:
- Phosphoglycerides: derived from 3 carbon GLYCEROL backbone; 2 FA chains attached to backbone; 3 major types.
- 1 FA is usually UNSATURATED, leading to KINK, which increases FLUIDITY.
- Head group consists of GLYCEROL, PHOSPHATE, then POLAR group.
- PTE an PC enriched in INTRACELLULAR membranes - Sphingolipids: derived from SPHINGOSINE backbone; SPHINGOMYELIN is major one.
- can contribute to formation of LIPID RAFTS alongside cholesterol - Glycolipids: often SPHINGOSINE backbone; CARBOHYDRATE always on EXTERNAL face.
- enriched in MYELIN
- Example: GM1 ganglioside used for entry of CHOLERA TOXIN. - Sterols: primarily CHOLESTEROL
- contains ALIPHATIC REGIONS, STEROL RING, and POLAR OH LOCATED NEAR MEMBRANE SURFACE IN BOTH LEAFLETS
PS has net ____ charge
PS has net NEGATIVE charge
Lipid rafts have ____ structure and can ______ subsets of membrane proteins to ____ function.
Lipid rafts have THICKER structure and can SEQUESTER subsets of membrane proteins to SEGREGATE function.
Integral membrane proteins are typically made up of _________ or _______.
Peripheral membrane proteins have lipid _____ attached that can ____ interact with membrane. Others associate with membrane via ___.
Integral membrane proteins are typically made up of 15-20 AA ALPHA HELIX or BETA BARREL.
Peripheral membrane proteins have lipid COVALENTLY attached that can REVERSIBLY (BC CAN BE REGULATED VIA CLEAVAGE) interact with membrane. Others associate with membrane via CHARGED-INTERACTIONS.
Things that can affect channel function:
- ___ channel blockers such as
- ________, which abolishes neuro-muscular transmission
- ________, which can also treat tachycardia
- ___ channel blockers, which are used to treat arrhythmias
- _____ or ____ toxins - _____ receptor at neuromuscular junction
- affected by ____, which is an antagonist at ___ binding site.
Things that can affect channel function:
- NA channel blockers such as
- TETRODOTOXIN, which abolishes neuro-muscular transmission
- LIDOCAINE, which can also treat tachycardia
- K channel blockers, which are used to treat arrhythmias
- SCORPION or CONE SNAIL toxins - NICOTINIC ACH receptor at neuromuscular junction
- affected by CURARE, which is an antagonist at ACH binding site.
Example of uniporter:
____ ____ transporter.
-Transport rate depends on _____, _____, and ____
Example of uniporter:
GLUT1 GLUCOSE transporter.
-Transport rate depends on CONCENTRATION GRADIENT, KM OF SOLUTE, AND FLIPPING RATE (VMAX)
Example of Symporter:
- ___/___ symporter
- _____ binding occurs so that binding of __ increases affinity of symporter for ____.
- Both sites need to be ______ for conformational switch that opens ____ _____ to other side of membrane.
- Allows transport of _____ _____ concentration gradient without ______.
Example of Symporter:
- NA/GLUCOSE symporter
- CO-OPERATIVE binding occurs so that binding of NA increases affinity of symporter for GLUCOSE.
- Both sites need to be OCCUPIED for conformational switch that opens SOLUTE BINDING SITES to other side of membrane.
- Allows transport of GLUCOSE AGAINST concentration gradient without DIRECT ENERGY EXPENDITURE.
Glucose transport from GI system through epithelial cells uses 2 different glucose transporters:
- _____; __ moves down gradient, ____ dragged inside. Located on ____ side of epithelial cell.
- ____; _____ moves down gradient.
Note: ___/___ transporter on ____ Surface to keep intracellular ___ [] low so the system can work.
Glucose transport from GI system through epithelial cells uses 2 different glucose transporters:
- SYMPORTER; NA moves down gradient, GLUCOSE dragged inside. Located on APICAL side of epithelial cell.
- UNIPORTER; GLUCOSE moves down gradient.
Note: NA/K PUMP transporter on BASAL Surface to keep intracellular NA [] low so the system can work.
2 Types of Active Transporters:
- P Type Pump: _______ with _ from ___
- ____ leads to conformational change
- ____ ions
-ABC Transporter: pumps _____ molecules rather than ____.
2 Types of Active Transporters:
- P Type Pump: AUTOPHOSPHORYLATION with P from ATP
- PHOSPHORYLATION leads to conformational change
- PUMPS ions
-ABC Transporter: pumps SMALL molecules rather than IONS.
Important P-Pumps:
__/____, 90% of membrane protein found in muscle cells
-since ___ is []d in ER, how is this reestablished after it’s release into cytoplasm during muscle contraction?
- Cavity in non-P-lated transporter binds ___
- ATP can bind and contribute _ for ____ of ___.
- When ___ is ____, conformation change occurs.
- Channel opens to ____ of ___ and releases ___.
Important P-Pumps:
CA2+/ATPase, 90% of membrane protein found in muscle cells
-since CA2+ is []d in ER, how is this reestablished after it’s release into cytoplasm during muscle contraction?
- Cavity in non-P-lated transporter binds CALCIUM
- ATP can bind and contribute P for P-LATION of ASP.
- When ASP is P-LATED, conformation change occurs.
- Channel opens to LUMEN of SR and releases CALCIUM.
Important P-Pumps:
NA/K ATPase where ___ ____ are transported against their [] gradients.
/ of cellular energy used to maintain this pump
- __ binds from inside of cell
- _____ of cytoplasmic face induces conformational change
- __ then transported and released on ____
- When __ outside of cell binds, _____ occurs and induces another conformational change, leading to entry of __ into cytoplasm
Important P-Pumps:
NA/K ATPase where BOTH IONS are transported against their [] gradients.
1/3 of cellular energy used to maintain this pump
- NA binds from inside of cell
- AUTO-PHOSPHORYLATION of cytoplasmic face induces conformational change
- NA then transported and released on OUTSIDE
- When K outside of cell binds, DEPHOSPHORYLATION occurs and induces another conformational change, leading to entry of K into cytoplasm
ABC Transporters:
- __ ATPase domains on each protein. Usually _____ bind to _____ bound state.
- ____ then binds and the _ ATPase binding domains ____, which produces conformational change that exposes the ___ to the ____ side of the membrane.
- _____ hydrolysis then releases substrate and prepares the transporter for another round.
Examples:
______ are found in tumor cells; more _____ drug is cleared from cytoplasm, reducing drug effects.
_____ resistance; amplified levels of _____ from ____ genome pump drug out.
ATP binding to ______ drives opening and closing of __ channel (exception of ABC transporter regulating ion flow)
ABC Transporters:
- TWO ATPase domains on each protein. Usually SMALL MOLECULES bind to NON-ATP bound state.
- ATP then binds and the TWO ATPase binding domains DIMERIZE, which produces conformational change that exposes the SUBSTRATE to the OPPOSITE side of the membrane.
- ATP hydrolysis then releases substrate and prepares the transporter for another round.
Examples:MULTIPLE DRUG RESISTANT (MDR) are found in tumor cells; more HYDROPHOBIC drug is cleared from cytoplasm, reducing drug effects.
CHLOROQUINE resistance; amplified levels of TRANSPORTER from MALARIA genome pump drug out.
ATP binding to CFTR drives opening and closing of CL channel (exception of ABC transporter regulating ion flow)