A synapse-specific carbohydrate at the neuromuscular junction: association with both acetylcholinesterase and a glycolipid

摘要: With the aim of investigating roles carbohydrates in synapse formation, we have characterized a synapse-specific saccharide at vertebrate neuromuscular junction. Two lectins similar specificity (Dolichos biflorus agglutinin, DBA, and Vicia villosa-B4 VVA-B4) stain synaptic but not extrasynaptic regions rat muscle fiber surface thus define carbohydrate. Using these other probes, show that carbohydrate moiety concentrated junction resembles N- acetylgalactosamine (GalNAc) linked beta-anomeric form to termini oligosaccharides. VVA-B4 also selectively stains junctions human, mouse, rabbit, guinea pig, chick, frog, axolotl, snake, fish, lamprey muscles, phylogenetic conservatism suggests synapse-related role for GalNAc beta- terminal saccharides. AChE from binds DBA- VVA-B4- agarose, is thereby identified as glycoconjugate bearing Assay isoforms reveals asymmetric, collagen-tailed forms, known be highly junction, bind DBA VVA-B4, while globular which are more widely distributed, do not. A second class GalNAc-bearing glycoconjugates demonstrable immunohistochemically with monoclonal antibodies stage-specific embryonic antigen (SSEA)-3 (Shevinsky et al., 1982) GM2 (Natoli 1986), recognize glycolipids. These junctions, where they glycolipid-like molecules distinguishable AChE. The association least 2 different synapse- specific raises possibility former plays determining property latter share, such concentration synapse.