ATP Binding Cassette Transporter, Subfamily B

**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 ATP-BINDING CASSETTE, SUB-FAMILY C PROTEINS they are two distinct subclasses of ATP-BINDING CASSETTE TRANSPORTERS, and have little sequence homology.

**Tree numbers:** - D09.400.430.890.020.400 - D12.776.157.530.100.075 - D12.776.157.530.450.074.500.500.250 - D12.776.395.550.020.400 - D12.776.543.550.192.400 - D12.776.543.585.100.200 - D12.776.543.585.450.074.500.500.250

**Synonyms:** - ATP Binding Cassette Transporter, Sub-Family B - ATP-Binding Cassette, Sub-Family B Proteins - Multidrug Resistance Proteins - P-Glycoproteins