Characterization of Oligomeric Human Half-ABC Transporter ATP-binding Cassette G2

Junkang Xu, Yang Liu, Youyun Yang, Susan Bates, Jian-Ting Zhang

Research output: Contribution to journalArticle

219 Citations (Scopus)

Abstract

Human ATP-binding cassette G2 (ABCG2, also known as mitoxantrone resistance protein, breast cancer-resistance protein, ABC placenta) is a member of the superfamily of ATP-binding cassette (ABC) transporters that have a wide variety of substrates. Overexpression of human ABCG2 in model cancer cell lines causes multidrug resistance by actively effluxing anticancer drugs. Unlike most of the other ABC transporters which usually have two nucleotide-binding domains and two transmembrane domains, ABCG2 consists of only one nucleotide-binding domain followed by one transmembrane domain. Thus, ABCG2 has been thought to be a half-transporter that may function as a homodimer. In this study, we characterized the oligomeric feature of human ABCG2 using non-denaturing detergent perfluoro-octanoic acid and Triton X-100 in combination with gel filtration, sucrose density gradient sedimentation, and gel electrophoresis. Unexpectedly, we found that human ABCG2 exists mainly as a tetramer, with a possibility of a higher form of oligomerization. Monomeric and dimeric ABCG2 did not appear to be the major form of the protein. Further immunoprecipitation analysis showed that the oligomeric ABCG2 did not contain any other proteins. Taken together, we conclude that human ABCG2 likely exists and functions as a homotetramer.

Original languageEnglish
Pages (from-to)19781-19789
Number of pages9
JournalJournal of Biological Chemistry
Volume279
Issue number19
DOIs
StatePublished - May 7 2004

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ATP-Binding Cassette Transporters
Adenosine Triphosphate
Proteins
Nucleotides
Gels
Mitoxantrone
Oligomerization
Octoxynol
Electrophoresis
Sedimentation
Detergents
Sucrose
Multiple Drug Resistance
Immunoprecipitation
Protein Binding
Placenta
Cells
Gel Chromatography
Breast Neoplasms
Substrates

ASJC Scopus subject areas

  • Biochemistry

Cite this

Characterization of Oligomeric Human Half-ABC Transporter ATP-binding Cassette G2. / Xu, Junkang; Liu, Yang; Yang, Youyun; Bates, Susan; Zhang, Jian-Ting.

In: Journal of Biological Chemistry, Vol. 279, No. 19, 07.05.2004, p. 19781-19789.

Research output: Contribution to journalArticle

Xu, Junkang ; Liu, Yang ; Yang, Youyun ; Bates, Susan ; Zhang, Jian-Ting. / Characterization of Oligomeric Human Half-ABC Transporter ATP-binding Cassette G2. In: Journal of Biological Chemistry. 2004 ; Vol. 279, No. 19. pp. 19781-19789.
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