Xenopus laevis egg jelly coats consist of small diffusible proteins bound to a complex system of structurally stable networks composed of high-molecular-weight glycoconjugates

Barry S. Bonnell, Donnie Reinhart, Douglas E. Chandler

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Abstract

The extracellular matrix surrounding Xenopus laevis eggs includes three morphologically distinct jelly layers designated J1, J2, and J3 from the innermost to outermost. Previously, using the quick-freeze, deep-etch, rotary-shadow technique, we found that each layer has a unique fibrillogranular ultrastructure. In this study, we show that the fibrillar network is composed of high-molecular-weight glycoconjugates, while the globular material consists of low-molecular-weight proteins some of which are released into the aqueous medium. Analysis by SDS-PAGE and differential staining of individually dissected jelly layers shows that both J1 and J2 contain three high-molecular-weight, acidic, Alcian blue-staining components (450, 630, and 900 kDa), while 13 contains two high-molecular-weight components that stain with PAS but not with Alcian blue. Each jelly layer also contains low-molecular-weight proteins from 75 to 250 kDa that do not stain with PAS or Alcian blue. Chromatography of whole egg jelly on a Sephacryl 500 column resulted in isolation of the major Alcian blue staining band (630 kDa) which eluted first, and two PAS staining bands which eluted second. Rotary-shadowing demonstrated that these high-molecular-weight glycoconjugates are long and branched, suggesting that they are major constituents of the jelly fiber network. SDS-PAGE analysis shows that these networks are stable for at least 16 hr after eggs are oviposited. In contrast, the low-molecular-weight globular proteins which constitute 30% of the total jelly protein are steadily released into the surrounding medium.

Original languageEnglish (US)
Pages (from-to)32-42
Number of pages11
JournalDevelopmental Biology
Volume174
Issue number1
DOIs
StatePublished - Jan 1 1996

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ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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