Transmembrane domain of ABC transporters

ABC transporter transmembrane domain is the main transmembrane structural unit of ATP-binding cassette transporter proteins, consisting of 6 to 10 alpha helixes that traverse the plasma membrane. Many members of the ABC transporter family (Pfam PF00005) have two such regions.

Source: Wikipedia — Transmembrane domain of ABC transporters (CC BY-SA 4.0)