CD36 is a ditopic glycoprotein with the N-terminal domain implicated in intracellular transport

Paola Gruarin, Rick F. Thorne, Douglas J. Dorahy, Gordon F. Burns, Roberto Sitia, Massimo Alessio

Research output: Contribution to journalArticle

Abstract

The CD36 receptor sequence predicts two hydrophobic domains located at the N- and C-termini of the protein, but there are conflicting reports as to whether the N-terminal uncleaved leader sequence functions as a transmembrane domain. To investigate the topology of CD36, we generated a panel of mutants lacking either one or both hydrophobic regions and analyzed their folding and transport in COS-7 cells. The N- and the C-terminal hydrophobic regions were both sufficient to anchor CD36 in the membrane, and a FLAG epitope inserted at the N-terminus was located intracellularly. These results indicate that CD36 adopts a ditopic configuration. Accordingly, neither N- nor C-terminal truncation mutants were secreted. Analysis with conformation-specific monoclonal antibodies showed that the N-terminal transmembrane domain truncated molecule was slowly transported through the exocytic pathway and largely accumulated intracellularly. Thus, dual membrane insertion dictates the correct topogenesis and seems to be necessary for efficient folding and intracellular transport. (C) 2000 Academic Press.

Original languageEnglish
Pages (from-to)446-454
Number of pages9
JournalBiochemical and Biophysical Research Communications
Volume275
Issue number2
DOIs
Publication statusPublished - Aug 28 2000

Keywords

  • CD36
  • Intracellular transport
  • Protein folding
  • Protein topology
  • Signal sequence

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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