Question

name and breifly three main classes for cell surface receptors

Answer 1

Cell surface receptors are of three types -

1. Ion channel receptors - this kind of receptor bind a specific ligand - a chemical molecule or in the form of electrical impulse causes passage of a specific ion though it. These are associated with rapid cellular response, muscle contraction, hormonal signalling etc.

2. G protein coupled receptor - in this a seven membrane alpha helical protein as-cats as a receptor, which contains 3 subunit. Activation of which causes separation of unit and attachment of it with GTP causing propagation of signal though difference secondary messenger like IP3, DAG and calcium ion and cyclic AMP etc. these ultimate cause phosphorylation of various intracellular protein and causes propagation of signals. they are associated with hormonal signalling, cell growth signalling etc.

3. Enzyme linked receptor - there are another kind of receptor for hormone signalling - example - receptor tyrosine kinase, which acts by forming a dimer and phosphorylation of self molecules, which then causes association of various biological molecules and phosphorylation and dephosphorylation of those molecules propagates the signal. receptor tyrosine kinase

G protein coupled receptor and ion receptor