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Selective release of peptides from lysosomes
1Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
The Journal of Biological Chemistry
|November 15, 1993
Summary
Lysosomes selectively release specific peptides, including potential T cell antigens, in vitro. This physiological process, observed with human fibroblast lysosomes, indicates controlled peptide export.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Lysosomes are key organelles for cellular degradation.
- The selective release of lysosomal contents, particularly peptides, is not fully understood.
- Peptide fragments are crucial for antigen presentation in T cell-mediated immunity.
Purpose of the Study:
- To investigate the selective release of peptides from lysosomes in vitro.
- To determine if lysosomal peptide release is a physiological process.
Main Methods:
- Incubation of a lysosomal fraction from human fibroblasts with endocytosed [3H]ribonuclease A.
- Analysis of radiolabeled molecules released into the medium and retained within lysosomes.
- Comparison of in vitro release with peptide release from intact cells.
Main Results:
- Lysosomes selectively released various radiolabeled peptides of appropriate size for T cell antigen presentation.
- A specific small peptide was predominantly released, while larger peptides and intact ribonuclease A were retained.
- Selective release patterns were consistent between in vitro lysosomal fractions and intact endocytosing cells.
Conclusions:
- Lysosomes exhibit selectivity in releasing peptides, suggesting a regulated mechanism.
- The observed in vitro peptide release mirrors in vivo processes, indicating physiological relevance.
- This selective release mechanism may play a role in immune surveillance and T cell activation.