Mouse liver PMP70 and ALDP: homomeric interactions prevail in vivo.
ALDP, ALDPR, PMP70 and PMP70R are half ATP-binding cassette (ABC) transporters of the mammalian peroxisomal membrane. By analogy with other members of this family, it is assumed that peroxisomal ABC transporters must dimerize to become functional units. However, not much is known regarding the type of dimers (i.e., homodimers and/or heterodimers) that are formed in vivo under normal expression conditions. In this work, we have characterized the quaternary structure of mouse liver PMP70 and ALDP. The PMP70 protein complex was purified to apparent homogeneity using a two-step purification protocol. The ALDP-containing protein complex was characterized by preparative immunoprecipitation experiments. In both cases, no evidence for the existence of heteromeric interactions or for the presence of accessory proteins in these ABC transporter protein complexes could be obtained. Our data indicate that the majority (if not all) of mouse liver PMP70 and ALDP are homomeric proteins.
Guimarães
Carla P
CP
Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, Porto, Portugal.
Domingues
Pedro
P
Aubourg
Patrick
P
Fouquet
Françoise
F
Pujol
Aurora
A
Jimenez-Sanchez
Gerardo
G
Sá-Miranda
Clara
C
Azevedo
Jorge E
JE
D000074063:ATP Binding Cassette Transporter, Subfamily D, Member 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000818:Animals; D004072:Digitonin / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D008099:Liver / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D021241:Spectrometry, Mass, Electrospray Ionization
C115572:ABCD1 protein, human; D000074063:ATP Binding Cassette Transporter, Subfamily D, Member 1; D018528:ATP-Binding Cassette Transporters; C489271:Abcd3 protein, mouse; D008565:Membrane Proteins; D004072:Digitonin