A late developmental change in lysosomal enzyme sulfation specific to newly synthesized proteins in Dictyostelium discoideum

George P. Livi, Nancy A. Woychik, Randall L. Dimond

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2 Scopus citations


During development in Dictyostelium discoideum, several lysosomal glycosidases undergo changes in post-translational modification that are thought to involve differences in the extent of sulfation or phosphorylation, and appear to be required for the maintenance of cellular enzyme activity late in development. We have used monoclonal antibodies specific to the lysosomal enzyme α-mannosidase-1 to study the major late (12 hr) developmental change in the modification system. Pulse-chase experiments performed both early and late in development reveal that the substrate for the late form of modification is restricted to newly synthesized α-mannosidase-1 precursor protein. We have identified one modification difference between the two developmentally distinct isozymes of α-mannosidase-1: 35SO4 pulse-chase data show that the newly synthesized "late" enzyme precursor is significantly undersulfated in comparison with the enzyme synthesized early in development. This apparent lack of sulfation is associated with the lack of acquisition of endoglycosidase H resistance. By contrast, an aggregation-deficient mutant, which is defective with regard to the accumulation of α-mannosidase-1 activity late in development, synthesizes the "early" sulfated form of the enzyme throughout development. We conclude that the late developmental change in post-translational modification specifically involves one of the biochemical steps in which the N-linked oligosaccharide side chains of the newly synthesized α-mannosidase-1 precursor are modified by sulfation.

Original languageEnglish (US)
Pages (from-to)293-300
Number of pages8
JournalDevelopmental Biology
Issue number2
StatePublished - Jun 1987
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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