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Nonhuman cells correctly sort and process the human lysosomal enzyme cathepsin D
G E Conner1, J A Udey, C Pinto
1Department of Anatomy and Cell Biology, University of Miami School of Medicine, Florida 33101.
Biochemistry
|April 18, 1989
Summary
This study investigates the later proteolytic cleavages of Cathepsin D (CTSD), a lysosomal enzyme. Findings show that human CTSD is correctly sorted and processed in diverse species, indicating conserved sorting mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Cathepsin D (CTSD) is a lysosomal enzyme undergoing multiple proteolytic cleavages.
- Early CTSD cleavages are understood, but later cleavages and their species-specific variations remain unclear.
Purpose of the Study:
- To investigate the functional significance and species-specific processing of later Cathepsin D cleavages.
- To determine if the cellular machinery for CTSD processing is conserved across species.
Main Methods:
- Isolated cDNA for human Cathepsin D.
- Expressed human CTSD in mammalian cells from species with different processing pathways.
- Analyzed proteolytic processing of human CTSD in these heterologous systems.
Main Results:
- Human CTSD was correctly sorted and processed to its two-chain form in all tested species.
- The processing pattern mirrored that observed in normal human fibroblasts.
- This indicates that the cellular sorting mechanism for CTSD is conserved.
Conclusions:
- The lysosomal sorting mechanism for human Cathepsin D is conserved across diverse mammalian species.
- Late proteolytic processing of CTSD is not dependent on species-specific processing enzymes, but rather on conserved sorting pathways.