Receptors Tutorial Flashcards
What do receptors do?
Receptors recognize and respond specifically to signal molecules
What are the 4 types of receptors? (4)
-Endocrine
-Paracrine
-Neuronal
-Contact-Dependant
What distance does endocrine communication act on?
Long distance: a cell signals to cells distributed widely in body
What distance does paracrine communication act on?
Extracellular signal molecules/mediator act locally: cell signals to neighbouring cells
What is an example of paracrine signalling?
Nitric oxide
What distance does neuronal communication act on?
Synapses may occur at long distances from cell bodies-long range communication, but message is delivered quickly and specifically (synapses)
What is a purpose of contact dependent signaling?
The immune system
What are the 4 signaling methods in receptors?
-Ligand-Gated ion channels (ionotropic receptors)
-G protein-coupled receptors
-Kinase-linked receptors
-Nuclear receptors
How long does each of these signalling mechanisms take to send a signal? (4)
-Ligand-Gated ion channels (ionotropic receptors)
-G protein-coupled receptors
-Kinase-linked receptors
-Nuclear receptors
Ligand-Gated ion channels (ionotropic receptors) - milliseconds
G protein-coupled receptors - seconds
Kinase-linked receptors - hours
Nuclear receptors – hours
How many transmembrane domains in an inotropic (Ligand-Gated) receptor?
2-4 transmembrane domains
How many transmembrane domains in GPCRs?
7 transmembrane domains
What do activated G proteins control the function of (follows binding of agonist to GPCR)?
Effectors
What does sympathetic and parasympathetic mean? (2)
Sympathetic– fight or flight
Parasympathetic – rest and digest
Describe signal transduction in heteromeric G proteins?
-Extracellular molecule binds to receptor, GDP exchanged for GTP
-Splits into a subunit and By subunit
-a subunit interacts with target protein so become activated and exchanged GTP for GDP
-By subunit reattaches to a subunit to form G protein
Which enzyme generated 2nd messenger cAMP?
Adenylate Cyclase
What is the target for cAMP?
PKA (Protein Kinase a)
(Phosphorylates L-type calcium channels, increased contraction)
What does Gq activate?
and which second messengers are generated? (2)
Phospholipase
IP3 and DAG
What is smooth muscle contraction regulated by?
Receptors coupled to Gq
