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41 Cards in this Set
- Front
- Back
What are the roles of the Endoplasmic Reticulum?
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-synthesis of lipids, glycolipids,
-secrete proteins -Store Ca2+ |
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Describe Gated transport
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- Occurs in the nucleus
- selective of large molecules, but lets small and cytosolic proteins pass freely - gate is complex and sorts well |
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Describe Transmembrane Transport
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-Occurs in mitochondria, ER
- machinery is used to direct proteins across membrane - ALWAYS need the right signature |
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What uses vesicular transport?
Describe what it is. |
ER, Golgi, Secretory and endocytic pathways
Ferry stuff from one compart to another - needs budding and fusion - maintain topography of membrane so that cell will recognize it |
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How are gated and transmembrane transport similar?
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Both need protein machinery to recognize, moniter, and assist transport
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Where are all proteins initially synthsized?
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cytoplasmic ribosomes, with sorting during or after translation
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What do adaptor proteins do?
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They bind to a sorting signal and bring the protein to the right compartment.
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Do cells ever generate new organelles?
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NO
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What kind of cells use signal patches?
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Golgi to Lysosome transport. Most most of everything else uses signal peptides in a straight line.
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Would a myelin sheath have more lipid or more protein?
A mitochondria? A plasma membrane? |
More lipid
Mire protein Even |
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What types of membrane proteins are there?
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Transmembrane, peripheral, Lipid associated
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What defines transmembrane proteins?
Examples? |
amphipathic proteins across bilayer
intrinsic -alpha helix with non-polar aas in center -flanked by charged aa's |
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What defines peripheral Proteins?
Examples? |
- Associate with an integral protein or a different comple, but not in it
-non-covalent -no need to disrupt, just use a high ionic wash or NaOH to isolate the protein |
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What defines a lipid assocated protein?
Examples? |
Protiens attached to bilayer by covalent attachment of a lipid anchor
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Where is the N-terminus in a type 1 protein?
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N terminus is either on the EC side or inside the lumen of an organelle.
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How do multi-span proteins work?
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-several transmembrane domains
- helices form bundles as they self-associate |
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How do you isolate an integral membrane protein?
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You disrupt the bilayer with detergents
- like triton mild, SDS harsh, or sterols |
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What types of lipid-anchored proteins are there?
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1-Covalent bonds to acyl chains on cytoplasm
2- covalently bound to polyisoprenoid anchors 3-Covalently bound to glycophosphatidylinositol (GPI) on EC face |
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What are the two fatty acid anchors?
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- Myristate- amide w/ N-term Gly, stable
-Palmitate- thioester w/cysteine, dinamic, made in cytoplasm then enzymatically placed on lipid |
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What do polyisoprene anchors do? - 2nd type of lipid-anchored proteins
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- Used for signal transduction or protein targetting
-either farnesyl w/ 3 isoprene units CAAX -or geranylgeranyl- 4 iso units CC link to cancer and RAS oncogene protein, stop farnesyl binding. |
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What are Glycophosphatidylinositols?
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-On EC face
-Takes integral proteins and cleaves of transmembrane domain,and GPI anchor added -then phosphoethanolamine links glycan-PI to C-terminus of target protein - proteins include cell surface enzymes, adhesive proteins, nutrient receptors |
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What terminus does the GPI anchor associate with?
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The C terminus
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What are glycophorins?
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- A family of large glycoproteins
-16 oligosaccharide chains with ltos of hexoses - strong negative charge to membrane surface - tail in cytoplasm interacts with cytoskeleton noncovalently |
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What do red bloodcells have to mediate bicorbanate and chloride exchange?
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An anion exchanger with dimers as a transmembrane protein.
w/ankryin |
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What are spectrins
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rod-like proteins that make a flexible 2D web
helps proteins to maintain network organization |
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What are porins made from?
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- Beta-barrel structure
- hydrophilic channels that allow solute passage up to 600 daltons. antiparallel arrangement in a channel. monomors form trimers - in backteria, mitochondria, chloroplasts |
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What about protein mobility?
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-no flip flop
-only lateral and rotational diffusion -patching and capping of antigens -depends on lipid content, other proteins -needs ATP |
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What are basket-shaped structures through which all substances pass into the nucleus?
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Nuclear pore complexes.
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What allows for movement of proteins and RNAs in and out of nucleus?
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Nucleo-cytoplasmic exchange
- proteins n like histones, polymerases - stuff out like tRNA and mRNA -some ribosomal proteins in then back out |
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What kind of molecules do the pores let in?
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- small solutes really quickly in
-macromolecules require active transport with ATP and GTP |
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What make up Nuclear localization sequences? (NLS)?
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-positively charged aa's - lysein, arginine, and proline
-no consensus not clipped off after transport - can be SV-40, bipartite, mat alpha 2 |
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Is the outer or the inner nuclear membrane covered in ribosomes?
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Outer - synthesized proteins transported into the nuclear space
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What are nuclear pores made out of?
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-luminal and column components,
-proteins of annular ring. spokes, filaments, fibrils of cages FG repeats for import recepters |
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What anchors the nuclear pore complex to the nuclear membrane?
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The transmembrane glycoprotein luminal component.
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Which side of the nucleus is the fibrilla elements?
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They are on both sides, but the cage/basket is on nuclear side
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Are cages 1 way or 2 way?
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1 way.
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What is the adaptor for Nuclear pore import?
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importin alpha
this binds to importin B later with the protein and associates with cytoplasmic fibrils |
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What is the roll of Ran GTPase in nuclear import?
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- stimulates transport with GAP and GEF
-GAP makes GDP -GEF makes GTP - GTP is made in nucleus, then enters the cytosol |
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What are nuclear export factors?
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- get rid of RNA's
-heterogeneous nuclear RNA-binding proteins - bind to Nups.NPC receptors -karyopherins are similar to NIR |
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What is an NES
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-nuclear export signal
- leucine rich -no consensus |
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What is NLS
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-nuclear localization signal.
- necessary and sufficient - basic complexes |