Cells have to
transmit and receive different signals, which can in turn coordinate cellular
activities and physiological processes occurring inside the body.
In fact, there
are 4 ways of which activation of receptors can control the activity of target
cells. The first way is by the direct control of ion channels. Ion channels may
be opened and signals can be transmitted by initiating a change in membrane
potential or by the influx of calcium ions. Nicotinic Ach receptors is an
example. The second way of control is by sending signals onto intracellular
receptors which can monitor the transcription of genes in our body. The
oestrogen receptor uses this method. As for the third method, the effector
enzyme can be directly controlled upon its activation. An example of this would
be the muscarinic Ach receptor.
In this essay we
shall delve into the discussion of a large class of receptor proteins inside
mammalian bodies, which are the G-protein coupled receptors. The activation of
G-protein coupled receptors is directly associated with the control of second
messengers. As the G-protein coupled receptors are activated, signals will be
sent from a plasma membrane to a specific enzyme or intracellular receptors,
initiating a flow of signaling cascades vital to maintain cellular processes taking
place inside the body.