19.3 Receptor-Ligand Interractions

Question 1

Two classes of receptors:

Answer 1

Nuclear Hormone receptors: Binds ligands within a cell.

Membrane-bound Receptors: Yeah…

Question 2

Hi

Answer 2

You are doing great, keep up the good work. Make sure to hydrate and take small 5-10min breaks periodically and stretch.

Question 3

Nuclear Hormone Receptors are found in what 2 places and they play a role as primarily what?

Answer 3

Are found in the cytosol or inside the nucleus. When in active form, cytosolic NHRs enter the membrane to bind to DNA. NHRs already in nuclear are already attached to DNA, but require a ligand to activate. Both types play a role as transcription factors.

Question 4

Membrane-bound Receptor Categories

Answer 4

Ion-linked, G Protein coupled, enzyme linked.

Question 5

Ion linked Receptor Functionality

Answer 5

When a ligand is bound, opens channel for an ionic molecule. Example: Acetylcholine-nicotine receptor.

Question 6

Cys-loop

Answer 6

Most common ion-channel receptor type. consists of four membrane-bound alpha-helices, and 5 alpha-helix subdomains.

Question 7

G Protein Coupled Receptor Functionality

Answer 7

Receptors that use heterotrimeric G-proteins to transmit extracellular signals.

Question 8

7-transmembrane Helix

Answer 8

Most common type of G-protein receptor.

Question 9

Enzyme-linked Receptors

Answer 9

When substrate binds to receptor, receptor then becomes an enzyme and catalyzes a reaction. Example: Insulin receptor.

Question 10

Receptor Tyrosine Kinase Functionality

Answer 10

When bound to substrate, causes the receptor to dimerize with another nearby receptor and auto-phosphorylate each other, and then the scaffolding protein.

Question 11

Agonist, Partial-Agonist and Antagonist

Answer 11

Agonist: binds to receptor, invokes full (or slightly modified) reaction.
Partial-Agonist: Binds to receptor, only invokes partial reaction.
Antagonist: binds to and blocks the receptor.

Question 12

Types of Agonists and Descriptions

Answer 12

Competitive Agonists: Competes with native ligand for binding site.
Noncompetitive Agonist: Does not compete with native ligand, but lowers the ability of the native ligand to bind to receptor.
Inverse Agonist: Effects the basal level of activity of receptor.

Question 13

The Langmuir Equation (cannot be used for receptors with allosteric sites)

Answer 13

Used to plot the percentage of bound sites (y) for a given concentration of substrate (x).