Receptors & Channels

Question 1

Receptor

Answer 1

Single or group of proteins that allow cell to collect info about surroundings

Dynamic: moving b/w active / inactive

normal points of control in physiologic processes

Question 2

Ligand

Answer 2

chemical messenger that binds and stabilizes a conformation of receptor
(small mlc / peptide)

Question 3

Conformation Change

Answer 3

receptor shape change ->
downstream signal transduction

Most receptors fluctuate b/w:
active /partially active /inactive

Question 4

Drugs hijack body system

Answer 4

Drugs mimic or block body’s own regulatory mlcs

don’t give cell new fx

Question 5

Ligand combine w/ receptor ….

Agonist
vs
Antagonist

Answer 5

to stimulate target organ (activate)
-stabilize active conformation

to interferes w/ naturally occurring agonist or agonist drug (prevent from activating)

Question 6

Potency vs efficacy

Answer 6

Potency = affinity for receptor
Efficacy = intrinsic activity
how much response

Question 7

Orthosteric antagonist

Answer 7

act on main binding site of receptor

Question 8

Allosteric antagonist

Answer 8

act on accessory binding site of receptor

Ex: Benzo (work on GABA but not at site)

Question 9

Pore Blocker

Answer 9

physically obstruct channel

Ex: local anesthetic

Question 10

Partial Agonist

Answer 10

weakly stabilize active state
OR
stabilize partially active state

-> antagonist if fill up all receptors

Question 11

Inverse Agonist

Answer 11

stabilize inactive state (shutdown)
-reverse baseline receptor activity

Ex: B blocker

Question 12

Non-Competitive Antagonist

Answer 12

< max response achievable w/ agonist

Question 13

Competitive Antagonist

Answer 13

Max response of agonist not reduced

Increase the amount of agonist required to produce same intensity of reponse

Question 14

Ligand Gated Ion Channels

Basics

Answer 14

In membrane
Direct coupling
Ex: Nicotinic, ACh, GABAa
oligomeric assembly of subunits around central pore

Question 15

G Protein-coupled receptors

Basics

Answer 15

In membrane [channel or enzyme effector]
Coupled w/ G protein or arrestin
Ex: muscarinic ACh, adrenorecptor

Monomeric/ oligomeric assembly of subunits
w/ 7 transmembrane helicies
w/ intracellular G protein coupling domain

Question 16

Receptor Kinases

Basics

Answer 16

In membrane
protein kinase effector
direct coupling
Ex: insulin, growth factor, cytokine receptor

Single transmembrane helix ->
links extracellular domain to intracellular kinase domain

Question 17

Nuclear receptors

basics

Answer 17

Located intracellular
Gene transcription = effector
Coupling via DNA
Ex: steroid receptors

Monomeric structure w/ receptor and DNA binding domains

Question 18

Excitatory
vs
Inhibitory

Answer 18

inside of cell charge -> 0
generally letting + ions into cell
[Depolarization]

Inside of cell charge -> more -
generally let -ions into cell (Cl-)
[Hyperpolarization]

Question 19

Ligand Gated Ion Channel
Speed
Families

Answer 19

Fast transmission
agonist binding = open pore

Cys Loop receptor
Ionotropic Glutamate Receptor

Question 20

Cys Loop receptor Family

Answer 20

Excitatory: Nicotinic ACh, 5HT-3
Inhibitory: Glycine, GABAa
Pentamer: 5 subunits
Named for disulfide bond b/w cisternes near N terminus

Question 21

Drugs that act on Cys Loop Receptors

Answer 21

Nic ACh: nicotine, varenicline (chantix)

GABAa: ambien (zolpidem), barbiturates, benzos, alcohol

Question 22

Dugs that act on Glutamate Receptors

Answer 22

NMDA: ketamine
AMPA: aniracetam

Question 23

nACh subunits

Answer 23

in NMJ contain:
apha beta gama delta subunits

Neuronal nACh:
alpha and beta subunits

Question 24

Chronic nicotine + nACh Receptors

Answer 24

(ie smoking) = upregulation

Question 25

nACh receptor activation States

Answer 25

Closed Open (ligand on) Desensitized (ligand on but not open) ^inactivated closed state

Question 26

Inotropic Glutamate Recptors

Answer 26

``` AMPA, NMDA, Kainate Tetramer: 4 subunits each has 4 transmembrane domains 2nd TM domain -> pore all 4 binded to open Excitatory pass Na/K+ ```

Question 27

NMDA receptor

Answer 27

can pass Na/K/Ca+ ions 2 subunits bind for glutamate 2 subunits bind for glycine blocked by Mg+ @ RMP

Question 28

Long Term Potentiation

Answer 28

More often neuron fires, stronger synapse gets | Ex: learning/ memory

Question 29

NMDA Receptor | -> coincidence receptor

Answer 29

NMDA pass Ca++ -> activate Ca Calmodulin Kinase 2 [CaMKII] -> AMPA receptors added to synapse > AMPA receptors =stronger synapse