Format

Send to:

Choose Destination
See comment in PubMed Commons below
Chem Biol. 1995 Nov;2(11):751-9.

Analysis of the conserved glycosylation site in the nicotinic acetylcholine receptor: potential roles in complex assembly.

Author information

  • 1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125, USA.

Abstract

BACKGROUND:

Assembly of the functional nicotinic acetylcholine receptor (nAChR) is dependent on a series of exquisitely coordinated events including polypeptide synthesis and processing, side-chain elaboration through post-translational modifications, and subunit oligomerization. A 17-residue sequence that includes a cystine disulfide and an N-linked glycosylation site is conserved in the extracellular domain of each of the nAChR subunits, and is involved in intersubunit interactions that are critical for assembly of intact, pentameric complexes. A polypeptide representing the relevant sequence from the alpha-subunit of the nAChR (Ac-Tyr-Cys-Glu-Ile-Ile-Val-Thr-His-Phe-Pro-Phe-Asp-Gln-Gln Asn-Cys-Thr-NH2) is small enough to allow detailed structural analysis, which may provide insight into the role of glycosylation in the maturation process that leads to ion-channel assembly. We therefore investigated the effect of N-linked glycosylation on the structure of this heptadecapeptide.

RESULTS:

Thermodynamic analysis shows that glycosylation alters disulfide formation in the loop peptide, shifting the equilibrium in favor of the disulfide. Spectroscopic studies reveal that the cis/trans amide isomer ratio of the proline is also affected by the modification, with a resultant shift in the equilibrium in favor of the trans isomer, even though the proline is several residues removed from the glycosylation site. Two-dimensional NMR analysis of the glycopeptide does not indicate the presence of any specific interactions between the carbohydrate and the peptide.

CONCLUSIONS:

These studies demonstrate that glycosylation can have a significant influence on disulfide formation and proline isomerization in a local peptide sequence. As both these processes are considered slow steps in protein folding, it is evident that N-linked glycosylation has important indirect roles that influence the folding of the receptor subunit and assembly of the pentameric complex.

PMID:
9383482
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk