Membrane Topology and Glycosylation of the Human Multidrug Resistance-associated Protein

• DOI: 10.1074/jbc.271.21.12322
• Publication Date: 2002-07-26T15:15:23Z
• Authors: Éva Bakos; Tamás Hegedüs; Zsolt Holló; Ervin Welker; Gábor E. Tusnády; Guido J.R. Zaman; Marcel J. Flens; András Váradi; Balázs Sarkadi
• Keywords: Tunicamycin; Membrane topology; Proteolysis

The membrane topology of the human multidrug resistance-associated protein (MRP) was examined by flow cytometry phenotyping, immunoblotting, and limited proteolysis in drug-resistant baculovirus-infected insect cells, expressing either glycosylated or underglycosylated forms this protein. Inhibition N-linked glycosylation cells tunicamycin did not inhibit transport function antibody recognition MRP, although its apparent molecular mass reduced from 180 kDa to 150 kDa. Extracellular addition trypsin chymotrypsin had no effect on while isolated membranes produced three large membrane-bound fragments. These experiments alignment MRP sequence with cystic fibrosis transmembrane conductance regulator (CFTR) suggest that similarly CFTR, contains a tandem repeat six helices, each followed nucleotide binding domain, C-terminal region is glycosylated. However, N-terminal an additional membrane-bound, area four five which seems be characteristic feature MRP-like ATP-binding cassette transporters.