Membrane topology and glycosylation of the human multidrug resistance-associated proteins

Éva Bakos, Tamás Hegedüs, Zsolt Holló, Ervin Welker, Gábor E. Tusnády, Guido J R Zaman, Marcel J. Flens, András Váradi, Balázs Sarkadi

Research output: Contribution to journalArticle

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Abstract

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

Original languageEnglish
Pages (from-to)12322-12326
Number of pages5
JournalJournal of Biological Chemistry
Volume271
Issue number21
Publication statusPublished - 1996

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Glycosylation
Multidrug Resistance-Associated Proteins
Topology
Membranes
Proteolysis
Cystic Fibrosis Transmembrane Conductance Regulator
Molecular mass
Tunicamycin
Tandem Repeat Sequences
ATP-Binding Cassette Transporters
Flow cytometry
Baculoviridae
Chymotrypsin
Immunoblotting
Trypsin
Insects
Flow Cytometry
Nucleotides
Cells
Antibodies

ASJC Scopus subject areas

  • Biochemistry

Cite this

Membrane topology and glycosylation of the human multidrug resistance-associated proteins. / Bakos, Éva; Hegedüs, Tamás; Holló, Zsolt; Welker, Ervin; Tusnády, Gábor E.; Zaman, Guido J R; Flens, Marcel J.; Váradi, András; Sarkadi, Balázs.

In: Journal of Biological Chemistry, Vol. 271, No. 21, 1996, p. 12322-12326.

Research output: Contribution to journalArticle

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