Most Signals Use this type of receptor
Cell surface receptors are also what kind of receptors
they are also transmembrane receptors
Proteins that span the membrane
They detect a signal outside of the cell and ?
relay the message to the inside of the cell
In all three main classes of cell-surface receptors, binding of the signal causes ?
binding of the signal causes a change in the receptor that relays the message onward without the need for the signal molecule itself to enter the cell
these three classes differ how?
in the identity of the intracellular signal that is generated upon perception of the extracellular signal
What are the three main classes of cell-surface receptors?
1. Ion-channel-linked receptors 2. G-protein linked receptors 3. Enzyme-linked receptors
What three things happen in regards to Ion channel linked receptors?
receptor opens or closes in response to binding of a signal, results in a flow of ions across the membrane, and produces an electrical current
G Protein linked Receptors: What happens upon binding a signal? what is this called?
The receptor activates a receptor-associated membrane bound protein called a GTP Binding Protein
GTP Binding Protein stands for?
heterotrimeric G protein or G protein for short
What does activated G protein do?
diffuse in plane of plasma membrane and bind a target enzyme or ion channel and initiate a cascade of effects
With Enzyme Linked receptors: the Binding of a signal does what?
switches on an intracellular enzyme activity
Some enzyme linked receptors have their own ? while others rely on associated enzymes
have their own catalytic domain
Are there more receptors than extracellular signals?
yes, there are more receptors than extracellular signals
some extracellular signals can activate more than one -----
can activate more than one receptor
activation of different receptors by the same signal can lead to what?
Cell surface receptors are also the targets of what?
Foreign substances such as drugs and poisons. they bind to cell surface receptors and interfere with our physiology and sensations. These substances may mimic a natural ligand and occupy the normal ligand-binding site or they may bind to a different site and blow or overstimulate the receptor's normal activity