Types Of Cell Surface Receptors

Question 1

Ion-channel linked receptors

Answer 1

Receptor and ion channel are present on the same protein molecule.
Transmembrane protein that opens or closes an ion channel upon binding to a chemical signal
Binding of a ligand to the receptor causes conformational change that opens of closes the channels
Allows ions to pass across the plasma membrane, changing the membrane potential.

Question 2

G-protein linked receptor

Answer 2

G-protein coupled receptors are integral membrane proteins that span the cell membrane seven times forming a helical structure.
Upon ligand binding, the GPCR undergoes conformational change, activating the g protein on the intracellular side.
Activated G protein then interacts with other proteins to initiate signalling cascade.

Question 3

What is structure of G-Proteins?

Answer 3

Composed of three subunits
Alpha, beta and gamma
Alpha subunit is bounded to GDP which is exchanged for GTP when GPCR undergoes conformational change.

Question 4

Enzyme-Linked Receptors

Answer 4

Transmembrane proteins with both a ligand-binding site outside and intrinsic enzyme catalytic unit inside
Spans the membrane one time
Binding of ligand to the extracellular domain causes conformational change that activates the enzymes, initiating signalling cascade