Detailed structural analysis of asparagine‐linked oligosaccharides of the nicotinic acetylcholine receptor from <i>Torpedo californica</i>

Shoji, Hiromichi; Takahashi, Nobutaka; Nishimura, Hiroshi; Ishikawa, Masami; Shimada, Ichio; Arata, Yoshiaki; Hayashi, Kyozo

doi:10.1111/j.1432-1033.1992.tb17090.x

Cited by 27 publications

(16 citation statements)

References 28 publications

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“…All four subunits of acetylcholine receptor are N-glycosylated (Shoji et al , 1992). N-linked glycosylation is required for the insertion of acetylcholine receptors into the plasma membrane through the regulation of subunit stability, folding, assembly and intracellular transport (Gehle and Sumikawa, 1991; Gehle et al , 1997).…”

Section: Resultsmentioning

confidence: 99%

Congenital myasthenic syndromes due to mutations inALG2andALG14

Cossins

Belaya

Hicks

et al. 2013

Brain

117

135

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Congenital myasthenic syndromes are a heterogeneous group of inherited disorders that arise from impaired signal transmission at the neuromuscular synapse. They are characterized by fatigable muscle weakness. We performed linkage analysis, whole-exome and whole-genome sequencing to determine the underlying defect in patients with an inherited limb-girdle pattern of myasthenic weakness. We identify ALG14 and ALG2 as novel genes in which mutations cause a congenital myasthenic syndrome. Through analogy with yeast, ALG14 is thought to form a multiglycosyltransferase complex with ALG13 and DPAGT1 that catalyses the first two committed steps of asparagine-linked protein glycosylation. We show that ALG14 is concentrated at the muscle motor endplates and small interfering RNA silencing of ALG14 results in reduced cell-surface expression of muscle acetylcholine receptor expressed in human embryonic kidney 293 cells. ALG2 is an alpha-1,3-mannosyltransferase that also catalyses early steps in the asparagine-linked glycosylation pathway. Mutations were identified in two kinships, with mutation ALG2p.Val68Gly found to severely reduce ALG2 expression both in patient muscle, and in cell cultures. Identification of DPAGT1, ALG14 and ALG2 mutations as a cause of congenital myasthenic syndrome underscores the importance of asparagine-linked protein glycosylation for proper functioning of the neuromuscular junction. These syndromes form part of the wider spectrum of congenital disorders of glycosylation caused by impaired asparagine-linked glycosylation. It is likely that further genes encoding components of this pathway will be associated with congenital myasthenic syndromes or impaired neuromuscular transmission as part of a more severe multisystem disorder. Our findings suggest that treatment with cholinesterase inhibitors may improve muscle function in many of the congenital disorders of glycosylation.

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Section: Resultsmentioning

confidence: 99%

Congenital myasthenic syndromes due to mutations inALG2andALG14

Cossins

Belaya

Hicks

et al. 2013

Brain

117

135

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“…301.8) and the one of the monosialyl 301.8 (code no. 1A1-301.8) were from nicotinic acetylcholine receptor from Torpedo californica (14). A tetraantennary oligosaccharide with bisecting N-acetylglucosamine (code no.…”

Section: Isolation Of Major Glycoproteins From Pigeon Egg White By Hpmentioning

confidence: 99%

N-Glycan Structures from the Major Glycoproteins of Pigeon Egg White

Takahashi

Khoo

Suzuki

et al. 2001

Journal of Biological Chemistry

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N-Glycans from major glycoproteins of pigeon egg white (ovotransferrin, ovomucoid, and ovalbumins) were enzymatically released and were reductively aminated with 2-aminopyridine, separated, and structurally characterized by mass spectrometry and a three-dimensional mapping technique using three different columns of high performance liquid chromatography (HPLC) (Takahashi, N., Nakagawa, H., Fujikawa, K., Kawamura, Y., and Tomiya, N. (1995) Anal. Biochem. 226, 139 -146). Twentyfive major N-glycan structures, all of them hitherto unknown, were identified as pyridylamino derivatives. Of these, 13 were neutral, 10 were monosialyl, and 2 were disialyl oligosaccharides. All N-glycans contain from one to four Gal␣(1,4)Gal␤(1,4) sequences at the nonreducing terminal positions and are devoid of fucose residues. NAcetylneuraminic acids were ␣(2,6)-linked only to ␤-galactose. The HPLC profiles of the N-glycans from four different glycoproteins were qualitatively very similar to each other, but not identical in the peak distributions. Monosialyl glycans were most abundant in all four glycoproteins, followed by neutral glycans. Disialyl glycans were lowest in ovotransferrin, and highest in ovomucoid. Triantennary structures with bisecting GlcNAc were predominant in ovotransferrin, and tetra-antennary (with and without bisecting GlcNAc-containing) structures were predominant in other glycoproteins. Penta-antennary structures (with a sialic acid and without bisecting GlcNAc residue) were also found in small quantities in all four glycoproteins. In contrast to the chicken egg white counterparts, which contain mostly high mannose and hybrid types, all N-glycan structures in the major pigeon egg white glycoproteins are complex type.The presence of galabiose (Gal␣4Gal) sequence in N-glycans in any animal is only rarely noted. The only documented presence of such a sequence in N-glycan was that found in turtle dove ovomucoid (1, 2). The only other recorded presence of galabiose sequence were both in the O-glycosides found in the Chinese swiftlet nest (3) and in an insect cell line Mamestra brassicae clone SPCMb-92-C6 (4). As shown in the preceding paper (5), we have demonstrated that galabiose sequence is abundantly present in pigeon egg white (PEW) 1 glycoproteins, and it always occupies the terminal positions of the multiantennary structures. In the major N-glycans from the pigeon ovalbumin, no sialylation is found on the branch that contains the galabiose sequence. In contrast, chicken ovalbumin contained mostly high mannose type and hybrid types (6, 7) whereas chicken ovomucoid contains mostly galactose-less complex type (8). The preceding paper (5) also notes that, in contrast to the chicken and other avian egg whites hitherto investigated, the N-glycans in pigeon egg white glycoproteins seem to be more "mature," containing more of the multiantennary complex type structures. In view of these unique structural features, we felt that detailed structural studies were in order, not only to understand the underlying evolutionary sig...

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“…About 20 kDa of the receptor's 290 kDa is carbohydrate. The majority of the AChR's oligosaccharide side chains is of the high-mannose type, the rest is of the sialylated complex type (Nomoto et al, 1986;Poulter et al, 1989;Shoji et al, 1992;Strecker et al, 1994). For a comprehensive discussion of the structural and functional details see Shoji et al (1992).…”

mentioning

confidence: 99%

The Emerging Three‐Dimensional Structure of a Receptor

Hucho

Tsetlin

Machold

1996

European Journal of Biochemistry

203

184

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The nicotinic acetylcholine receptor is the neurotransmitter receptor with the most-characterized protein structure. The amino acid sequences of its five subunits have been elucidated by cDNA cloning and sequencing. Its shape and dimensions (approximately 12.5 nmX8 nm) were deduced from electronmicroscopy studies. Its subunits are arranged around a five-fold axis of pseudosymmetry in the order (clockwise) aI,yaLGP. Its two agonistkompetitive-antagonist-binding sites have been localized by photolabelling studies to a deep gorge between the subunits near the membrane surface. Its ion channel is formed by five membrane-spanning (M2) helices that are contributed by the five subunits. This finding has been generalized as the Helix M2 model for the superfamily of ligand-gated ion channels. The binding site for regulatory non-competitive antagonists has been localized by photolabelling and site-directed-mutagenesis studies within this ion channel.Therefore a three-dimensional image of the nicotinic acetylcholine receptor is emerging, the most prominent feature of which is an active site that combines the agonist/competitive-antagonist-binding sites, the regulatory site and the ion channel within a relatively narrow space close to and within the bilayer membrane.

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Detailed structural analysis of asparagine‐linked oligosaccharides of the nicotinic acetylcholine receptor from Torpedo californica

Cited by 27 publications

References 28 publications

Congenital myasthenic syndromes due to mutations inALG2andALG14

Congenital myasthenic syndromes due to mutations inALG2andALG14

N-Glycan Structures from the Major Glycoproteins of Pigeon Egg White

The Emerging Three‐Dimensional Structure of a Receptor

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