Receptors and Second Messengers Flashcards
What is a signaling molecule?
A compound produced in one cell, and used to transmit a message to one (or many) other cells
What is a receptor?
A specific protein that is the site for binding of a signaling molecule
What is an effector?
The protein or mechanism that is ultimately activated by a receptor
What is a second messenger?
A small intracellularly diffusible signaling molecule. In G protein signaling systems, second messengers are modulated by primary effectors
What is a ligand?
A compound that binds to a specific site on a protein. A subtype of signaling molecule.
What is an agonist?
A ligand that binds to a receptor and activates the effector
What is an antagonist?
A ligand that binds to a receptor but does not activate effector. Prevents agonists from binding to receptor.
What is a full agonist?
Binds to receptor and fully activates effector
What is a partial agonist?
Binds to a receptor but only partially activates effector
What is an inverse agonist?
Binds to receptor and inactivates (turns off) effector (produces the opposite effect as an agonist)
What is a competitive antagonist?
Competes with an agonist for the same binding site on a receptor
What is a non-competitive antagonist?
Binds to a receptor at a discrete site and changes the maximal response without altering the potency
What is the difference between an inverse agonist and an antagonist?
Inverse agonist still does something to the effector. Antagonist does not.
What are the four types of signaling between cells?
Contact dependent, paracrine, synaptic, and endocrine
Describe contact dependent signaling
Signaling molecule is NOT diffusible. Cells must be in direct contact. Important during development and for some types of immune function.
Describe paracrine signaling
Signaling molecules are released into the extracellular space, where they may act on cells that express receptors for the signaling molecule. Paracrine signals may be terminated by cells that take up and/or enzymes that break down the signaling molecule.
ACTS LOCALLY
Describe synaptic signaling
Allows very specific and very RAPID delivery of HIGHLY concentrated signaling molecules at large distances from the cell soma. The primary signaling molecules released from synaptic terminals are neurotransmitters.
Describe endocrine signaling
Allows relatively SLOW and non-specific delivery at LOW concentrations via the BLOODstream. The signaling molecules released from endocrine cells are HORMONES.
What are the two major classes of receptors?
Cell surface receptors (exist on/in the plasma membrane) and cytosolic/nuclear receptors (found inside the cell)
What are the three classes of cell surface receptors? Which two are the most important?
Ion linked, G-protein linked, and Enzyme linked
Ion and G-Protein linked are the most important
Ion channel linked receptors are also known as…
ligand gated ion channels and ionotropic receptors
Ligand gated ion channels are gated by a small number of ligands called…
Neurotransmitters (e.g. glutamate, GABA, glycine, acetylcholine, serotonin, etc)
True or False: Ligand gated ion channels are selective for certain ions.
True and False…can be selective, can be non-selective
When ligand gated ion channels open, the ions will flow (with/against) their concentration gradient
With