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30 Cards in this Set
- Front
- Back
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structural proteins |
compose the cytoskeleton, anchoring proteins, and much of the extracellular matrix; generally fibrous in nature most common examples: collagen elastin keratin actin tubulin |
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motor proteins |
have one or more heads capable of force generation through a conformational change; have catalytic activity, acting as ATPases to power movement; muscle contraction, vesicle movement within cells, and cell motility are the most common applications of motor proteins most common examples: myosin kinesin dynein |
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binding proteins |
bind a specific substrate, either to sequester it in the body or hold its concentration at a steady state |
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cell adhesion molecules (CAMs) |
allow cells to bind to other cells or surfaces include: cadherins integrins selectins |
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cadherins |
a type of cell adhesion molecule (CAM); calcium-dependent glycoproteins that hold similar cells together |
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integrins |
a type of cell adhesion molecule (CAM); have two membrane-spanning chains (means that they are attached to the outside of the membrane with two projections) and permit cells to adhere to proteins in the extracellular matrix; some also have signaling capabilities |
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selectins |
a type of cell adhesion molecule (CAM); allow cells to adhere to carbohydrates on the surfaces of other cells and are most commonly used in the immune system
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antibodies (or immunoglobulins, Ig) |
used by the immune system to target a specific antigen, which may be a protein on the surface of a pathogen or a toxin immunoglobulins contain a constant region and a variable region; the variable region is responsible for antigen binding two identical heavy chains (the Y looking part) and two identical light chains (the V looking part) form a single antibody; they are held together by disulfide linkages and noncovalent interactions |
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ion channels |
can be used for regulating ion flow into or out of a cell three main types: ungated channels voltage-gated channels ligand-gated channels |
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ungated channel |
an ion channel which is always open; responsible for maintaining the resting membrane potential |
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voltage-gated channel |
an ion channel which is open within a range of membrane potentials |
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ligand-gated channel |
an ion channel which is open in the presence of a specific binding substance, usually a hormone or neurotransmitter |
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enzyme-linked receptors |
participate in cell signaling through extracellular ligand binding and initiation of second messenger cascades |
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G protein-coupled receptors |
have a membrane-bound protein associated with a trimeric G protein; also initiate second messenger systems ligand binding engages the G protein GDP is replaced with GTP; the α subunit dissociates from the β and γ subunits the activated α subunit alters the activity of aldenylate cyclase or phospholipase C GTP is dephosphorylated to GDP; the α subunit rebinds to the β and γ subunits |
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electrophoresis |
uses a gel matrix to observe the migration of proteins in response to an electric field types: native PAGE SDS-PAGE isoelectric focusing |
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native PAGE |
type of electrophoresis which maintains the protein's shape, but results are difficult to compare because the mass-to-charge ratio differs for each protein |
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SDS-PAGE |
type of electrophoresis which denatures the proteins and masks the native charge so that comparison of size is more accurate, but the functional protein cannot be recaptured from the gel |
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isoelectric focusing |
type of electrophoresis which separates proteins by their isoelectric point (pI); the protein migrates toward an electrode until it reaches a region of the gel where pH=pI of the protein |
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chromatography |
separates protein mixtures on the basis of their affinity for a stationary phase or a mobile phase types: column chromatography ion-exchange chromatography size-exclusion chromatography affinity chromatography |
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column chromatography |
uses beads of a polar compound, like silica or alumina (stationary phase), with a nonpolar solvent (mobile phase) |
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ion-exchange chromatography |
uses a charged column (the beads) and a variably saline eluent |
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size-exclusion chromatography |
relies on porous beads; larger molecules elute first because they are not trapped in the small pores |
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affinity chromatography |
uses a bound receptor or ligand and an eluent with free ligand or a receptor for the protein of interest |
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X-ray crystallography |
the primary method used to determine protein structure after the protein is isolated |
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nuclear magnetic resonance (NMR) spectroscopy |
another method also used to determine protein structure after protein is isolated |
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hydrolysis |
a reaction involving the breaking of a bond in a molecule using water; can be used to determine amino acid composition |
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Edman degradation |
sequential degradation which can be used for amino acid sequencing; proceeds from the amino (N-) terminus |
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activity levels for enzymatic samples are determined by |
following the process of a known reaction, often accompanied by a color change |
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protein concentration is determined |
colorimetrically, either by UV spectroscopy or through a color change reaction methods include: BCA assay Lowry reagent assay Bradford protein assay |
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Bradford protein assay |
uses a color change from brown-green to blue to measure protein concentration |
