Abc transporter protein

 ABC transporters are a family of transport proteins that primarily move small molecules across membranes. ABC transporters are composed of two ATPase domains, when ATP binds to an ABC transporter, the two domains dimerize, and when ATP is hydrolyzed, the two domains dissociate. This conformational change is thought to activate further changes within the membrane itself, revealing binding sites. In doing so this allows the transport of small molecules across the membrane.

 Alberts, B et al., 2007. Molecular Biology of the Cell, 5th edition. Garland Science, pg. 663