Coexpression of ATP-binding cassette proteins ABCG5 and ABCG8 permits their transport to the apical surface

Gregory A. Graf, Wei Ping Li, Robert D. Gerard, Ingrid Gelissen, Ann White, Jonathan C. Cohen, Helen H. Hobbs

Research output: Contribution to journalArticle

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Abstract

Mutations in either ATP-binding cassette (ABC) G5 or ABCG8 cause sitosterolemia, an autosomal recessive disorder of sterol trafficking. To determine the site of action of ABCG5 and ABCG8, we expressed recombinant, epitope-tagged mouse ABCG5 and ABCG8 in cultured cells. Both ABCG5 and ABCG8 underwent N-linked glycosylation. When either protein was expressed individually in cells, the N-linked sugars remained sensitive to Endoglycosidase H (Endo H). When ABCG5 and ABCG8 were coexpressed, the attached sugars were Endo H-resistant and neuraminidase-sensitive, indicating that the proteins were transported to the trans-Golgi complex. The mature, glycosylated forms of ABCG5 and ABCG8 coimmunoprecipitated, consistent with heterodimerization of these two proteins. The Endo H-sensitive forms of ABCG5 and ABCG8 were confined to the endoplasmic reticulum (ER), whereas the mature forms were present in non-ER fractions in cultured hepatocytes. Immunoelectron microscopy revealed ABCG5 and ABCG8 on the plasma membrane of these cells. In polarized WIF-B cells, recombinant ABCG5 localized to the apical (canalicular) membrane when coexpressed with ABCG8, but not when expressed alone. To our knowledge this is the first direct demonstration that trafficking of an ABC half-transporter to the cell surface requires the presence of its dimerization partner.

Original languageEnglish (US)
Pages (from-to)659-669
Number of pages11
JournalJournal of Clinical Investigation
Volume110
Issue number5
DOIs
StatePublished - Sep 2002

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Glycoside Hydrolases
Carrier Proteins
Adenosine Triphosphate
Reticulum
Proteins
ATP-Binding Cassette Transporters
Immunoelectron Microscopy
Neuraminidase
Dimerization
Golgi Apparatus
Sterols
Plasma Cells
Glycosylation
Endoplasmic Reticulum
Epitopes
Hepatocytes
Cultured Cells
B-Lymphocytes
Cell Membrane
Mutation

ASJC Scopus subject areas

  • Medicine(all)

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Coexpression of ATP-binding cassette proteins ABCG5 and ABCG8 permits their transport to the apical surface. / Graf, Gregory A.; Li, Wei Ping; Gerard, Robert D.; Gelissen, Ingrid; White, Ann; Cohen, Jonathan C.; Hobbs, Helen H.

In: Journal of Clinical Investigation, Vol. 110, No. 5, 09.2002, p. 659-669.

Research output: Contribution to journalArticle

Graf, Gregory A. ; Li, Wei Ping ; Gerard, Robert D. ; Gelissen, Ingrid ; White, Ann ; Cohen, Jonathan C. ; Hobbs, Helen H. / Coexpression of ATP-binding cassette proteins ABCG5 and ABCG8 permits their transport to the apical surface. In: Journal of Clinical Investigation. 2002 ; Vol. 110, No. 5. pp. 659-669.
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