Chapter 3 Nonenzymatic Protein Function/Analysis

Question 1

What are structural proteins and what are some examples.

Answer 1

They make up the cytoskeleton, anchoring proteins and a majority of the extracellular matrix. They are fibrous in nature.

Examples include collagen, elastin, keratin, actin, and tubulin.

Question 2

What is the function of motor proteins and what are some examples?

Answer 2

Motor proteins generate force through confirmational change. ATPases power movement.

Examples include myosin, kinesin, dynein.

Question 3

What is a binding protein?

Answer 3

They bind to specific substrates either to sequester it in the body (hide it so it stays in active) or hold its concentration at a steady state.

Question 4

What are the three different types of cell adhesion molecules?

Answer 4

Cadherins
Integrins
Selectins

Question 5

Cadherins

Answer 5

Calcium dependent like a proteins that holds similar cells together

Question 6

Integrins

Answer 6

Permits cells to adhere to proteins in the extracellular matrix.

Some have signaling capabilities.

Question 7

Selectins

Answer 7

Allows cells to adhere to carbohydrates on the surfaces of other cells.

Most commonly used in the immune system.

Question 8

What is an antibody?

Answer 8

Also known as immunoglobin’s. Used by the immune system to target a specific antigen.

Antigens may be proteins on the surface of a pathogen or a toxin.

Question 9

What region of the immuno globin is responsible for antigen binding?

Answer 9

The variable region

Question 10

What is an ion channel and what are the three main types?

Answer 10

Ion channels are use for regulating ion flow into or out of the cell.

The three main types are:
Ungated channels- always open
Voltage gated channels- open within a range of membrane potentials
Ligand gated channels-open in the presence of a specific binding substance. Neurotransmitter or Hormone.

Question 11

Electrophoresis

Answer 11

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

Question 12

Native Page

Answer 12

Maintains the proteins shape.

Most useful for comparing the molecular size or charge of proteins known to be similar in size from other analytic methods like SDS page or size exclusion chromatography.

Question 13

SDS Page

Answer 13

Denatures proteins. Masks native charge so the comparison of size is more accurate.

Functional proteins cannot be recaptured from the gel.

Question 14

What is isoelectric focusing?

Answer 14

Separates proteins by their isoelectric point. The protein migrates toward an electrode untill it reaches a region of the gel where the pH is equal to the PI of the protein.

Question 15

What is chromatography?

Answer 15

Separate a mixture of proteins based on the basis of their affinity for a stationary phase or mobile phase.

Question 16

What is column chromatography?

Answer 16

Uses beads of a polar compound like silica or alumina (stationary phase) with a nonpolar solvent (mobile phase).

Question 17

What is eluded first in column chromatography?

Answer 17

Non-polar molecules are elites first because they are have a higher affinity for the mobile phase.

Question 18

What is ion exchange chromatography?

Answer 18

It uses a charged column and a variably Saline eluent.

Question 19

What is eluded first in ion chromatography?

Answer 19

If the stationary phase contains a cation. The cation will be eluded first because it will repel the stationary phase.

Question 20

What is size exclusion chromatography?

Answer 20

Separates a protein mixture based on size. Larger compounds are alluded first because smaller compounds get stuck in the porous beads.

Question 21

What is affinity chromatography?

Answer 21

Uses a bound receptor or ligand and an eluent with a free ligand or a receptor for the protein of interest.

Question 22

How is protein structure primarily determined?

Answer 22

Through x-ray crystallography. This occurs after the protein is isolated although NMR can also be used.