Nonenzymatic Protein Function And Protein Analysis Flashcards

1
Q

structural proteins

A

compose the cytoskeleton, anchoring proteins, and much of the extracellular matrix
most common: collagen, elastin, keratin, actin, tubulin
generally fibrous in nature

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2
Q

motor proteins

A

have one or more heads capable of force generation through a conformational change
have catalytic activity, acting as Atlases to power movement
muscle contraction, vesicle movement within cells, and cell motility are most common applications
common ex: myosin, kinesin, dynein

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3
Q

binding proteins

A

bind a specific substrate, either to sequester it in the body or hold its concentration at a steady rate

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4
Q

cell adhesion molecules (CAMs)

A

allow cells to bind to other cells or surfaces

cadherins, integrins, selectins

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5
Q

cadherins

A

calcium-dependent glycoproteins that hold similar cells together

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6
Q

integrins

A

have two membrane-spanning chains and permit cells to adhere to proteins in the extracellular matrix
some also have signaling abilities

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7
Q

selectins

A

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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8
Q

antibodies (immunoglobulins, Ig)

A

used by the immune system to target a specific antigen
contain a constant region and variable region; the variable region is responsible for antigen binding
two identical heavy chains and two identical light chains form a single antibody; they are held together by disulfide linkages and noncovalent interactions

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9
Q

antigen

A

may be a protein on the surface of a pathogen (invading organism) or toxin

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10
Q

ion channels

A

can be used for regulating ion flow into or out of a cell

three main types: ungated, voltage-gated, ligand-gated

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11
Q

ungated channels

A

ion channels that are always open

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12
Q

voltage-gated channels

A

ion channels that are open within a range of membrane potentials

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13
Q

ligand-gated channels

A

ion channels that open in the presence of a specific binding substance, usually a hormone or neurotransmitter

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14
Q

enzyme-linked receptors

A

participate in cell signaling through extracellular ligand binding and initiation of second messenger cascades

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15
Q

G-protein coupled receptors

A

have a membrane-bound protein associated with a trimeric G protein
also initiate second messenger systems
1. ligand binding engages the G protein
2. GDP is replaced with GTP; the α subunit dissociates from ß and γ subunits
3. the activated α subunit alters the activity of adenylate cyclase or phospholipase C
4. GTP is dephosphorylated to GDP; the α subunit rebinds to the ß and γ subunits

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16
Q

electrophoresis

A

uses a gel matrix to observe the migration of proteins in response to an electric field

17
Q

native PAGE

A

maintains the protein’s shape, but results are difficult to compare because the mass-to-charge ratio differs for each protein

18
Q

SDS-PAGE

A

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

19
Q

isoelectric focusing

A

separates proteins by their pI; the protein migrates toward an electrode until it reaches a region of the gel where pH=pI of the protein

20
Q

chromatography

A

separates protein mixtures on the basis of their affinity for a stationary phase or mobile phase

21
Q

column chromatography

A

uses beads of a polar compound, like silica or alumina (stationary phase), with a non polar solvent (mobile phase)

22
Q

ion-exchange chromatography

A

uses a charged column and a variably saline fluent

23
Q

size-exclusion chromatography

A

relies on porous beads

larger molecules elute first because they are not trapped in the small pores

24
Q

affinity chromatography

A

uses a bound receptor or ligand and an fluent with free ligand or a receptor for the protein of interest

25
X-ray crystallography
method of determining protein structure after protein is isolated NMR can also be used
26
Edman degradation
determines amino acid sequencing through sequential degradation
27
Bradford protein assay
determine protein concentration uses a color change from brown-green to blue to test for protein most common