N-Glycans on the link domain of human HARE/Stabilin-2 are needed for hyaluronan binding to purified ecto-domain, but not for cellular endocytosis of hyaluronan

Edward N. Harris, Simon Parry, Mark Sutton-Smith, Madhu S. Pandey, Maria Panico, Howard R. Morris, Stuart M. Haslam, Anne Dell, Paul H. Weigel

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

The hyaluronic acid receptor for endocytosis (HARE)/Stabilin-2 is the primary systemic scavenger receptor for 13 ligands including hyaluronan (HA), heparin and chondroitin sulfates. Most ligand-binding sites are within the 190 kDa isoform, which contains ~25 kDa of N-glycans and is the C-terminal half of the full-length 315 kDa HARE. Glycoproteomic analyses of purified recombinant human 190-HARE ecto-domain identified a diverse population of glycans at 10 of 17 consensus sites. The most diversity (and the only sialylated structures) occurred at N2280, within the HA-binding Link domain. To determine if these N-glycans are required for HA binding, we created human Flp-In 293 cell lines expressing membrane-bound or soluble ecto-domain variants of 190-HARE(N2280A). Membrane-bound HARE lacking Link domain N-glycans mediated rapid HA endocytosis, but purified 190-HARE (N2280A) ecto-domain showed little or no HA binding in ELISA-like, HA-HARE pull-down assays or by surface plasmon resonance analysis (which detected very high apparent affinity for 190-HARE ecto-domain binding to HA; Kd = 5.2 nM). The results indicate that Link domain Nglycans stabilize interactions that facilitate HA binding to HARE.

Original languageEnglish (US)
Article numbercwq057
Pages (from-to)991-1001
Number of pages11
JournalGlycobiology
Volume20
Issue number8
DOIs
Publication statusPublished - Apr 14 2010

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Keywords

  • Coated pit mediated
  • Conformation
  • Glycosaminoglycan turnover
  • HA binding affinity
  • Stabilin-2

ASJC Scopus subject areas

  • Biochemistry

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