39-kDa receptor-associated protein (RAP) facilitates secretion and ligand binding of extracellular region of very-low-density-lipoprotein receptor: Implications for a distinct pathway from low-density-lipoprotein receptor

Atsushi Sato, Yoshimi Shimada, Joachim Herz, Tokuo Yamamoto, Hisato Jingami

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

We have expressed the extracellular regions of the low-density-lipoprotein (LDL) receptor and the very-low-density-lipoprotein (VLDL) receptor, along with the full-length forms of the receptors, in insect cells in a baculovirus system. The extracellular region of the LDL receptor has been secreted successfully into the culture medium, and it retained the capacities of binding 125I-labelled LDL and β-VLDL. In contrast, the extracellular region of the VLDL receptor remained intracellular and it did not bind 125I-β-VLDL. This difference in expression behaviour between the homologous regions of the two receptors suggests that the two receptor systems are different in receptor-protein maturation or protein targeting. Next we developed the co-expression system with 39-kDa receptor-associated protein (RAP). This co-expression facilitated the secretion of the extracellular region of the VLDL receptor into the culture medium and the secreted receptor bound 125I-β-VLDL. The VLDL receptor remaining intracellular that was co-expressed with RAP also showed binding capacity to 125I-β-VLDL, implying that the existence of RAP prevented receptor-protein aggregation or improved protein-folding status of the truncated VLDL receptor. On the other hand, expression of the extracellular region of the LDL receptor was not facilitated by RAP co-expression. Thus RAP plays an essential role in maintenance of the active conformation and secretion of the extracellular region of the VLDL receptor.

Original languageEnglish
Pages (from-to)377-383
Number of pages7
JournalBiochemical Journal
Volume341
Issue number2
DOIs
Publication statusPublished - 1999 Jul 15

Keywords

  • Chaperone
  • Co-expression
  • LDL receptor
  • VLDL receptor

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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