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Glycan localization within the human interphotoreceptor matrix and photoreceptor inner and outer segments.

Oxford University Press
Publication Date
  • Adolescent
  • Adult
  • Aged
  • Aged
  • 80 And Over
  • Metabolism: Biotin
  • Carbohydrate Sequence
  • Chemistry: Extracellular Matrix
  • Galanthus
  • Histocytochemistry
  • Humans
  • Metabolism: Lectins
  • Middle Aged
  • Molecular Sequence Data
  • Metabolism: Oligosaccharides
  • Chemistry: Photoreceptors
  • Plant Lectins
  • Classification: Polysaccharides
  • Research Support
  • Non-U.S. Gov'T
  • Chemistry: Retina
  • Chemistry: Rod Outer Segments
  • Biology
  • Chemistry
  • Medicine


Glycoconjugates are likely to be of fundamental importance in the complex interactions between photoreceptors and the retinal pigment epithelium, but few have been characterized, especially in human tissue. As a preliminary step towards determining their biological functions in health and disease, a lectin-based histochemical study of the glycan expression of human outer retina was performed on glutaraldehyde-fixed, semi-thin, resin-embedded sections. The interphotoreceptor matrix and photoreceptor plasma-lemmata expressed complex bisected and non-bisected biantennary and/or triantennary N-glycans. In addition, both the rod and cone outer segments bound strongly Galanthus nivalis agglutinin (which binds terminal Man alpha 1, 3Man-) and the rod outer segments bound selectively the isolectin II of Bandeiraea simplicifolia (which binds terminal GlcNAc-). The cilia of the rods and cones were labelled selectively with Glycine max agglutinin after sialidase pretreatment. Four putative glycan outer sequences were identified within the interphotoreceptor matrix: (i) sialylated glycans with subterminal GalNAc alpha 1,3GalNAc-sequences; (ii) a sialylated type with subterminal N-acetyl-lactosamine residues; (iii) Gal beta 1,3GalNAc alpha 1- residues which were substituted with sialic acid except in the cone matrix sheath; (iv) GalNAc alpha 1,6Gal beta 1- residues which were substituted in part with sialic acid. The sialic acid expression throughout was predominantly of the 2,3-linked form with lesser amounts of 2,6-linkage, and rod-associated structures (including the surrounding interphotoreceptor matrix) were labelled more strongly with the sialic acid-binding lectins than cone-associated structures (including the cone matrix sheath).

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