Peptide specificity and lipid activation of the lysosomal transport complex ABCB9 (TAPL)

J Biol Chem. 2008 Jun 20;283(25):17083-91. doi: 10.1074/jbc.M801794200. Epub 2008 Apr 22.

Abstract

The lysosomal ABC transporter associated with antigen processing-like (TAPL, ABCB9) acts as an ATP-dependent polypeptide transporter with broad length selectivity. To characterize in detail its substrate specificity, a procedure for functional reconstitution of human TAPL was developed. By intensive screening of detergents, ideal solubilization conditions were evolved with respect to efficiency, long term stability, and functionality of TAPL. TAPL was isolated in a two-step procedure with high purity and, subsequently, reconstituted into proteoliposomes. The peptide transport activity of reconstituted TAPL strongly depends on the lipid composition. With the help of combinatorial peptide libraries, the key positions of the peptides were localized to the N- and C-terminal residues with respect to peptide transport. At both ends, TAPL favors positively charged, aromatic, or hydrophobic residues and disfavors negatively charged residues as well as asparagine and methionine. Besides specific interactions of both terminal residues, electrostatic interactions are important, since peptides with positive net charge are more efficiently transported than negatively charged ones.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry*
  • Antigens / chemistry
  • Asparagine / chemistry
  • Biochemistry / methods
  • Biological Transport
  • Detergents / chemistry
  • Detergents / pharmacology
  • Humans
  • Lipids / chemistry
  • Methionine / chemistry
  • Peptide Library
  • Peptides / chemistry*
  • Protein Structure, Tertiary
  • Static Electricity
  • Substrate Specificity
  • Tissue Distribution

Substances

  • ABCB9 protein, human
  • ATP-Binding Cassette Transporters
  • Antigens
  • Detergents
  • Lipids
  • Peptide Library
  • Peptides
  • Asparagine
  • Methionine