Engelsk definition
A subfamily of transmembrane proteins from the superfamily of ATP-BINDING CASSETTE TRANSPORTERS that are closely related in sequence to ATP BINDING CASSETTE TRANSPORTER, SUBFAMILY B, MEMBER 1. When overexpressed, they function as ATP-dependent efflux pumps able to extrude lipophilic drugs (especially ANTINEOPLASTIC AGENTS) from cells, causing multidrug resistance (DRUG RESISTANCE, MULTIPLE). Although ATP BINDING CASSETTE TRANSPORTER, SUBFAMILY B share functional similarities to MULTIDRUG RESISTANCE-ASSOCIATED PROTEINS they are two distinct subclasses of ATP-BINDING CASSETTE TRANSPORTERS, and have little sequence homology.