Cloning and characterization of human adenosine 5'-triphosphate-binding cassette, sub-family A, transporter 2 (ABCA2)

Cancer Res. 2001 Apr 15;61(8):3339-47.

Abstract

We have isolated the full-length cDNA for human ATP-binding cassette, sub-family A, member 2 transporter (ABCA2). The ORF of this cDNA encodes a protein consisting of 2436 amino acids with apparent molecular weight of M(r) 270,000. Accordingly, ABCA2 is the largest known mammalian ABC transporter described thus far. Analysis of mRNA expression levels indicated that ABCA2 is highest in human brain and has a broad expression pattern in a panel of tumor cell lines. Using specific antibodies to ABCA2 and various organelle marker proteins, ABCA2 was found to colocalize with the lysosomal/endosomal marker LAMP1, forming discrete, punctate intracellular vesicles. In ABCA2-transfected cells, the transporter also colocalized with a fluorescently labeled steroid analogue, estramustine. The sequestration of the steroid into the lysosomal/endosomal compartment indicates a potential substrate specificity for ABCA2. Furthermore, the presence of a lipocalin signature motif in the ABCA2 sequence suggests a possible broad role for this protein in the transport of steroids, lipids, and related molecules.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / biosynthesis
  • ATP-Binding Cassette Transporters / genetics*
  • ATP-Binding Cassette Transporters / metabolism
  • Amino Acid Sequence
  • Animals
  • Blotting, Northern
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • DNA, Complementary / isolation & purification
  • Estramustine / pharmacokinetics
  • Gene Expression Profiling
  • Humans
  • Mice
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Protein Conformation
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Subcellular Fractions / metabolism
  • Substrate Specificity
  • Tissue Distribution
  • Tumor Cells, Cultured

Substances

  • ABCA2 protein, human
  • ATP-Binding Cassette Transporters
  • Abca2 protein, mouse
  • DNA, Complementary
  • RNA, Messenger
  • Estramustine

Associated data

  • GENBANK/AF178941