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39 Cards in this Set
- Front
- Back
lipid raft
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thicker region of the plasma membrane that contains a lot of glycosphingolipids and contain receptors for toxins
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integral protein diseases
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blood clotting issues, cancer - integrin
myasthenia gravis - AChR - excitation responses affected cystic fibrosis - CFTCR - Cl- channel - misfolded protein can't make it to cell surface |
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peripheral protein diseases
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muscular dystrophy - dystrophin
cardiac arrhythmias - ankyrin - ion channels in cardiac membrane sickle cell disease - spectrin proteinuric kidney disease - dynamin - cell permeability |
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GPI linked protein disease
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cancer - Ras
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How does integrin link actin to the ECM?
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2 methods
One end of integrin is bound to the ECM and passes through the plasma membrane. It binds to Talin, which forms a complex with Vinculin and together they bind Actin. Integrin again binds to ECM and passes through PM but binds to alpha actinin which then binds actin. |
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How does blood clotting work and how does Integrilin prevent the process from taking place?
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Fibrinogen normally binds to integrilin molecules on 2 different platelets, forming a clot. Integriling (RGD tripeptides) bind to Integrin, thus blocking Fibrinogen and preventing the blood from clumping.
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Describe the Spectrin membrane skeleton in RBCs
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Spectrin molecules (long thin proteins) bind to Ankyrin (globular proteins) and actin. Ankyrin interacts with Band 3, and integral membrane protein, to connect this meshwork to the PM. Actin also binds to Band 4.1 which binds to glycophorin, an integral membrane protein.
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basic mechanism of muscular dystrophy
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Cells that lack dystrophin leak MG53, a key component of cell membrane repair, when they are damaged, leading to degeneration of muscle
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N cadherin
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provides signal for neurite formation
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Zonula Occludens (Tight Junction)
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prevent intercellular transport
transmembrane proteins = claudin and occuldin (claudin is a water channel woven within occludins) ZO-1 and ZO-2 are cytoplasmic proteins that bind to Actin |
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Zonula Adherens / Adheren Junctions
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transmembrane protein = cadherin
cytoplasmic proteins = catenin --> vinculin --> alpha actinin which bind actin filaments |
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Macula Adherens / Desmosome
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found in areas with a lot of stress like cardiac muscle and skin
transmembrane proteins = desmoglein and desmocollin attachment plaque is made of desmoplakin and plakoglobin which binds intermediate filaments |
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Gap Junction
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Consists of connexons, which are made of 6 cylindrical subunits called connexins
cytoplasmic proteins = ZO-1 and Drebrin that bind actin Mutations: Connexin 26 - inherited deafness Connexin 50 - cataracts in lens |
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Hemidesmosome
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adhere epithelial cells to basal lamina
transmembrane proteins = integrin and BP 180 cytoplasmic proteins = BP230 and plectin which bind intermediate filaments |
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Kartagener's syndrome
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a tyope of Primary Cilia Dyskinesia
absence of dynein arms on microtubules leads to immotile cilia in the respiratory tract |
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primary cilia
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sensors of fluid flow
passive bending as a result of fluid flow in a kidney tubule opens polycystin 1&2, mechanoreceptor calcium channels |
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major functions of cell membranes
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structure, protection, activation of cell, transport, cell to cell interaction
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functions of integral membrane proteins
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channel (pore), transporter (carrier), receptor, enzyme, cytoskeleton anchor, cell identity marker
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subdomains of ER
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smooth, rough, nuclear, export sites
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unfolded protein response
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series of signaling cascades that respond to environmental stress and developmental cues - slow down translation and increase molecular chaperones that assist in correct folding of proteins
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chronically activated UPR
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occurs in conditions of low O2, high or low blood glucose - leads to inflammation in obesity and atherosclerosis, diabetes, cancer
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enlarged, dilated cisternae of ER
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hydropic swelling of liver cells due to toxic injury
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progeria
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normally lamin A is farnesylated and then the lipid is cleaved off but in progeria the cleavage site is deleted so lamin becomes progerin --> abnormal nuclear morphology, progerin in mitotic cytoplasm, binucleation
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post translational targeting / import
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proteins are assembled on free ribosomes and are distributed to cytoplasm, nucleus, peroxisome, mitochondria
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co-translational targeting / import
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proteins are made on RER ribosomes and are distributed to the ER, Golgi, plasma membrane and lysosome
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How are proteins targeted to the ER?
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Signal Recognition Particle (SRP) binds to signal sequence of mRNA, arresting translation. SRP interacts with a docking protein on the ER membrane and is then released, allowing translation to continue. Signal sequence interacts with translocator channel protein so ribosome - ER interaction is stabilized. Signal peptide is cleaved off by signal petidase and is digested. Protein is released into lumen of ER.
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actin mRNA zip codes
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3' untranslated sequence - needed to localize actin mRNA to specific regions of the cell - can block this polarization using oligonucleotides
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Cystic Fibrosis Transmembrane Conductance Regulator
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Cl- channel in epithelial cells
in CF, it gets misfolded so it can't reach the membrane can add chaperones in the hopes of getting it to properly fold - BiP (binding protein) |
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Smooth ER functions
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conversion of glycogen to glucose in the liver, storage of calcium in the sarcoplasmic reticulum, detoxification via oxidative enzymes like P450s, synthesis of steroid hormones in gonads and the adrenal cortex
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COPII
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associates with the membrane at ER export sites to facilitate budding
coat is assembled via Sar1, Sec 23 - Sec 24, Sec 13 - Sec 31 concentrates cargo and bends ER membrane to create transport vesicle for delivery to Golgi (anterograde) |
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parts of the Golgi
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ERGIC (ER - Golgi Intermediate Compartment)
cis face medial face trans face trans Golgi Network |
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I Cell Disease
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defect in adding Mannose 6 phosphate to lysosomal enzymes ==> there's a build up of substances in lysosomes and the proteins are excreted instead of imported into lysosome
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Vesicular tubular cluster
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aka ERGIC
mediates trafficking between ER and Golgi - facilitates sorting of cargo |
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COPI
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coats vesicles that move Golgi to ER (retrograde)
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V SNARES and T SNARES
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transmembrane proteins on vesicles and target sites that bind together, leading to immediate fusing of membranes
can be destroyed by toxic enzymes, affecting exocytic processes which can lead to failure of muscle to contraction |
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types of endocytosis
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phagocytosis, macropinocytosis, clathrin mediated, caveolin mediated, plain ole pinocytosis
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Familial Hypercholesterolemia
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High serum levels of LDL due to a mutation in binding to receptors (normally found in coated pit regions of the plasma membrane)
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clathrin mediated endocytosis
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AP2 binds to transmembrane receptor and clathrin to form a lattice structure. Dynamin helps pinch off the pit. Inside the cell, clathrin and adaptins disassemble via HSC70 and auxillin (accessory molecules) and are recycled.
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caveloae
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invaginations in membrane - lipid subdomains rich in sphingolipids and cholesterol
coated with caveolin protein preferred means of entrance by pathogens because it doesn't feed into lysosomal pathways |