ABC transporter protein knowledge page

The ATPase Binding Cassette (ABC) transporter superfamily is made of proteins can either import or export substrates from the cell. It uses ATP to perform the action, where the stoichiometry of ATP used will vary depending on the type of ABC. Substrates transported range from ions to macromolecules.

It is found that the ABC possesses

- two transmembrane domains, for substrate passage

- two nucleotide (ATP or ADP) binding domains

We consider the 'alternating site' model. Here, it is thought that at rest, the ABC is bound by ADP. When ATP is bound instead (and ADP is released) and the substrate is also bound, the ABC changes conformation to face the inner or outer side of the cell, in order to release the substrate. Energy required for the change is obtained from the hydrolysis of ATP into ADP.

Model

The below images show the bond graph diagram of the channel operating under normal physiological conditions.

Full model

Reduced (steady state) model