what are the 3 types of membrane proteins?
- membrane-bound receptors
- membrane-bound metabolic enzymes
- membrane transport proteins
what do membrane transport proteins do?
move polar molecules across the hydrophobic membrane
list and describe the 2 ways that membrane transport molecules move molecules across hydrophobic membranes and the energy dependence of each
- passive: down concentration gradient; energy independent
- active: up concentration gradient; energy dependent
give 2 example of passive membrane transporters
- gramicidin A; an antibiotic polypeptide
- porins; ion channels made of beta barrel proteins
describe the structure of porin passive transport proteins
alternating hydrophobic and hydrophilic residues
describe how the structure of membrane transport enables their function and give an example
helices form substrate-selective channels; like the K+ channel protein,which allows for passive transport of K+ and excludes other ions like Na+
what do aquaporins allow for?
passive transport of water
what are the 3 types of active transporters? and what are the 2 main categories of the 3 types?
either primary or secondary
1. primary active transporter
2. secondary active antiporter
3. secondary active symporter
describe how primary active transporters work
ATP turnover drives the movement of molecules up their concentration gradient
describe how secondary active antiporters work
molecules moving down their concentration gradients drive other molecules up their concentration gradients (opposite directions)
describe how secondary active symporters work
molecules moving down their concentration gradient drive other molecules moving up their concentration gradients (in same direction)
what does the Na+/K+ ATPase membrane protein do? generally and specifically
creates membrane potential important for neurons by pumping 3 Na+ out of the cell and bringing 2 K+ into the cell (both against concentration gradients)
what drives the conformational shift of the Na+/K+ ATPase membrane protein?
ATP hydrolysis
what is the Na+/I- secondary symporter essential for? generally then specific ion movement
essential for thyroid hormone biosynthesis by bring one I- and 2 Na+ into the cell
what is the Na+/I- secondary symporter coupled to?
coupled to the Na+/Kt ATPase transporter
what does SERCA stand for?
sarco/endoplasmic reticulum Ca2+ ATPase
what is SERCA responsible for?
uptake of Ca2+ from cytosol into sarcoplasmic reticulum lumen
where is SERCA abundant and as what?
abundant in animal muscle cells as a Ca2+ transporter
what kind of transporter is SERCA?
a primary active transporter
what does SERCA promote?
muscle relaxation
what is phospholamban?
a protein that attaches to SERCA when dephosphorylated, preventing SERCA from working
what deactivates phospholamban and what is the result?
phosporylation deactivates phospholamban, causing it to dissociate from SERCA and allow muscle contraction to begin
what 2 things phosphorylate phospholamban and where?
- adrenaline phosohorylates Ser16 by protein kinase A
- high Ca2+ phosphorylates Thr17 by Ca2+/calmodulin kinase II
give the 4 steps of the SERCA mechanism
- ATP hydrolysis and phosphorylation of Asp351 releases H+ and binds Ca2+ in the transmembrane helices, causing a conromfationa change
- ADP dissociated, casuing M2 to open toward the luminal side and release Ca2+
- ATP binding repositions M2 to trap H+
- Asp351 dephosphorylates
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Chapter 1106
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Chapter 2108
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Chapter 499
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Chapter 6.1 and 6.2131
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Chapter 6.3-6.441
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Chapter 756
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Chapter 7.3 Chymotrypsin35
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Chapter 7.4 Enzyme Kinetics65
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Chapter 7.5 Enzyme Regulation32
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3.1-3.2 DNA and RNA Organization86
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9.1 and 9.2 Glycolysis Intro and Simple Sugars46
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9.3 Glycolysis Pathway51
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9.4-9.5 Glycolysis Regulation24
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10.1-10.2 Step 0 of citrate cycle54
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10.3 Citric Acid Cycle reactions37
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10.4-10.5 Regulation of the citrate cycle18
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11.1 Chemiosmotic Theory40
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11.2 Electron Transport Chain60
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11.3 ATP Synthase22
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11.4-11.5: Regulation of Oxidative Phosphorylation34
