N-linked glycosylation is required for optimal AT(1a) angiotensin receptor expression in COS-7 cells

Suman Jayadev, Roger D. Smith, Gowraganahalli Jagadeesh, Albert J. Baukal, László Hunyady, Kevin J. Catt

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Abstract

The nature and role of glycosylation in AT1 angiotensin receptor (AT1-R) function were investigated by expressing glycosylation-deficient influenza hemagglutinin (HA) epitope-tagged rat AT(1a)-Rs (HA-AT(1a)-Rs) in COS-7 cells. All three asparagine residues (Asn4, Asn176, Asn188) contained within consensus sites for N-linked glycosylation could be glycosylated in Cos-7 cells and appeared to be glycosylated on the endogenous AT1-R in bovine adrenal glomerulosa cells. Heterogeneity of glycosylation at each site accounted for the broad migration pattern of the AT1-R in SDS-PAGE. Mutation at each glycosylation site, either alone or in combination, had little effect on ligand binding parameters (although the N4K mutant had higher affinity) or signaling activity. However, an increasing number of mutated glycosylation sites was associated with decreasing cell surface receptor expression, which was minimal for the unglycosylated N4K/N176Q/N188Q receptor. Decreased surface expression of mutant HA-AT(1a)-Rs was correlated with decreased total cell receptor content as revealed by immunoblotting with an anti-HA antibody. These findings suggest that glycosylation enhances receptor stability, possibly by protecting nascent receptors from proteolytic degradation.

Original languageEnglish
Pages (from-to)2010-2017
Number of pages8
JournalEndocrinology
Volume140
Issue number5
DOIs
Publication statusPublished - Jan 1 1999

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ASJC Scopus subject areas

  • Endocrinology

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