Nonenzymatic Protein Function and Protein Analysis

Question 1

Structural Proteins

Answer 1

generally fibrous

Include: collagen, elastin, keratin, actin, and tubulin

Question 2

Motor Proteins

Answer 2

capable of force generation through a conformational change

Include: myosin, kinesin, and dynein

Question 3

Binding Proteins

Answer 3

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

Question 4

Cell Adhesion Molecules (CAM)

Answer 4

bind cells to other cells or surfaces

Include: cadherins, integrins, and selectins

Question 5

Antibodies (Immunoglobulins, Ig)

Answer 5

target a specific antigen, which may be a protein on the surface of a pathogen or a toxin

Question 6

Collagen

Answer 6

makes up most of the extracellular matrix of connective tissue, strong and flexible (trihelical fiber)

Question 7

Elastin

Answer 7

in extracellular matrix of connective tissue and primary role is to stretch and recoil

Question 8

Keratins

Answer 8

intermediate filament proteins found in epithelial cells and they contribute to mechanical integrity of the cell

Question 9

Actin

Answer 9

makes up microfilaments and the thin filaments in myofibrils, have a positive and negative side that allow motor proteins to unidirectionally travel

Question 10

Tubulin

Answer 10

Makes up microtubules, which provide structure, chromosome separation in mitosis/meiosis, and intracellular transport

Question 11

Myosin

Answer 11

primary motor protein that interacts with actin, it is the thick filament in a myofibril, its neck is responsible for the power stroke

Question 12

Kinesin

Answer 12

key role in aligning chromosomes during metaphase and depolymerizing mircotubules in anaphase

bring vesicles towards the positive end of a microtubule

Question 13

Dyenins

Answer 13

important in the movement of cilia and flagella

bring vesicles towards the negative end of a microtubule

Question 14

Cadherins

Answer 14

groups of glycoproteins that mediate calcium depended cell adhesion

Question 15

Integrins

Answer 15

group of proteins with two membrane spanning chains which are important in binding to and communicating with the extracellular matrix

Question 16

Selectins

Answer 16

bind to carbohydrate molecules that project from other cell surfaces

Question 17

Ion Channels

Answer 17

Permit facilitated diffusion of charges particles

Question 18

Facilitated Diffusion

Answer 18

passive transport via diffusion down a concentration gradient through a pore created by a transmembrane protein

Question 19

Ungated Channels

Answer 19

totally unregulated, always open

Question 20

Voltage-Gated Channels

Answer 20

gate is regulated by the membrane potential change near the channel, closed under resting conditions

Question 21

Ligand-Gated Channels

Answer 21

binding of a specific ligand to the channel causes it to open or close

Question 22

Enzyme Linked Receptors

Answer 22

membrane receptors that display catalytic activity in response to ligand binding, three domains:
membrane spanning domain
ligand-binding domain
catalytic domain

Question 23

G-Protein Coupled Receptors

Answer 23

Integral membrane proteins that are involved in signal transduction. Binding of ligand increases affinity of receptor for G protein and G protein binding switches it to an active state. Use a heterotrimeric G protein to transmit signals. They have an intracellular link to guanine nucleotides.

Question 24

Electorphoresis

Answer 24

subjects compounds to an electric field, which moves them according to their net charge and size, negatively charges compounds migrate towards the positive anode and the positively charged compounds migrate towards the negative cathode

standard medium is polyacrylamide gel

Question 25

Native PAGE

Answer 25

polyacrylamide gel electrophoresis (PAGE), is a method for analyzing proteins in their natural state, and is limited by the varying mass-to-charge and mass-to-size ratios of cellular proteins

most useful to compare size or charge

native protein can be recovered after

Question 26

SDS-PAGE

Answer 26

completes PAGE and then adds SDS detergent to stain and visualize sections

useful to separate proteins based on mass alone

Question 27

Isoelectric Focusing

Answer 27

Proteins are separated based on their isoelectric point

mixture is placed in a gel with a pH gradient (acidic anode, basic cathode) and an electric field is generated across the gel

Question 28

Column Chromatography

Answer 28

column filled with silica or aluminum and gravity moves the solvent down the column

size and polarity separate the compounds

Question 29

Ion-Exchange Chromatography

Answer 29

beads in column are coated in a charged substance to bind compounds of opposite charge

salt gradient used to elute charged molecules stuck to column

Question 30

Size-Exclusion Chromatography

Answer 30

beads in column have pores of varying sizes that allow small compounds to enter and large compounds move through faster

Question 31

Affinity Chromatography

Answer 31

customized column to bind with a specific substrate and is eluted by washing column with a free receptor for the protein

Question 32

Protein Structure best assessed using

Answer 32

X-ray Crystallography and NMR spectroscopy

Question 33

Amino Acid composition best assessed using

Answer 33

Complete protein hydrolysis and subsequent chromatographic analysis

Question 34

Concentration best assessed using

Answer 34

Spectroscopy (often UV) or in an assay