Defining the Intracellular Localization Pathways followed by Lysosomal Enzymes in Dictyostelium discoideum

James A. Cardelli, Nancy A. Woychik, David L. Ebert, George S. Golumbeski, Robert C. Mierendorf, Randall L. Dimond

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19 Scopus citations


This chapter describes the biochemical and genetic methods used to define both the intracellular pathways followed by lysosomal enzymes and the molecular nature of the “sorting” signals found on the proteins. Using biochemical methods, the lysosomal enzymes α-man and β-glu in Dictyostelium are synthesized as precursor polypeptides that are cotranslationally translocated into the lumen of the endoplasmic reticulum (ER) and N-glycosylated. The precursors move at different rates from the RER to the Golgi complex, where they are sulfated and sorted into two classes. One class, containing the majority of the precursor polypeptides, is directed to lysosomes where they are rapidly cleaved to mature forms of the enzymes. The other class of precursors is rapidly secreted from cells. The different intracellular transport rates for the α-man and β-glu precursors support the existence of a transport-mediating receptor. The genetic approach involved the isolation and characterization of mutants altered in the secretion, modification, processing, and/or localization of lysosomal enzymes. Through biochemical analysis of these mutants, one can identify and characterize the molecular components involved in the processing and transport of this group of enzymes.

Original languageEnglish (US)
Pages (from-to)139-155
Number of pages17
JournalMethods in cell biology
Issue numberC
StatePublished - Jan 1987
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Cell Biology

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