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J Biol Chem. 1999 Jun 4;274(23):16249-56.

Protease trafficking in two primitive eukaryotes is mediated by a prodomain protein motif.

Author information

1
Department of Pathology, University of California, San Francisco, California 94121, USA.

Abstract

Trypanosome protozoa, an early lineage of eukaryotic cells, have proteases homologous to mammalian lysosomal cathepsins, but the precursor proteins lack mannose 6-phosphate. Utilizing green fluorescent protein as a reporter, we demonstrate that the carbohydrate-free prodomain of a trypanosome cathepsin L is necessary and sufficient for directing green fluorescent protein to the lysosome/endosome compartment. A proper prodomain/catalytic domain processing site sequence is also required to free the mature protease for delivery to the lysosome/endosome compartment. A nine-amino acid prodomain loop motif, implicated in prodomain-receptor interactions in mammalian cells, is conserved in the protozoa. Site-directed mutagenesis now confirms the importance of this loop to protease trafficking and suggests that a protein motif targeting signal for lysosomal proteases arose early in eukaryotic cell evolution.

PMID:
10347181
[Indexed for MEDLINE]
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