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Updated: Mar 25, 2026
Single-Molecule Localization Microscopy of Membrane Proteins using Single-Antibody Labeling
Published on: March 20, 2026
A monoclonal antibody raised against bacterially expressed MPV17 sequences shows peroxisomal, endosomal and lysosomal
Hans Weiher1,2, Haymo Pircher3, Pidder Jansen-Dürr4
1Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Martinistrasse 52, 20251, Hamburg, Germany. hans.weiher@fh-brs.de.
Abstract:
Recessive mutations in the MPV17 gene cause mitochondrial DNA depletion syndrome, a fatal infantile genetic liver disease in humans. Loss of function in mice leads to glomerulosclerosis and sensineural deafness accompanied with mitochondrial DNA depletion. Mutations in the yeast homolog Sym1, and in the zebra fish homolog tra cause interesting, but not obviously related phenotypes, although the human gene can complement the yeast Sym1 mutation. The MPV17 protein is a hydrophobic membrane protein of 176 amino acids and unknown function. Initially localised in murine peroxisomes, it was later reported to be a mitochondrial inner membrane protein in humans and in yeast. To resolve this contradiction we tested two new mouse monoclonal antibodies directed against the human MPV17 protein in Western blots and immunohistochemistry on human U2OS cells. One of these monoclonal antibodies showed specific reactivity to a protein of 20 kD absent in MPV17 negative mouse cells. Immunofluorescence studies revealed colocalisation with peroxisomal, endosomal and lysosomal markers, but not with mitochondria. This data reveal a novel connection between a possible peroxisomal/endosomal/lysosomal function and mitochondrial DNA depletion.
Insights
Recessive mutations in the MPV17 gene cause fatal infantile liver disease. New research shows the MPV17 protein localizes to peroxisomes, endosomes, and lysosomes, not mitochondria, revealing a novel link to mitochondrial DNA depletion.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- Recessive MPV17 gene mutations cause fatal infantile mitochondrial DNA depletion syndrome.
- MPV17 protein's cellular localization has been contradictory, reported in both peroxisomes and mitochondria.
Purpose of the Study:
- To resolve the contradictory localization of the MPV17 protein.
- To investigate the function of MPV17 in relation to mitochondrial DNA depletion.
Main Methods:
- Generated and utilized two new mouse monoclonal antibodies against human MPV17.
- Performed Western blots and immunohistochemistry on human U2OS cells.
- Conducted immunofluorescence studies to assess co-localization with various cellular markers.
Main Results:
- A specific monoclonal antibody recognized a 20 kD protein absent in MPV17-negative cells.
- Immunofluorescence revealed MPV17 co-localizes with peroxisomal, endosomal, and lysosomal markers.
- MPV17 did not co-localize with mitochondrial markers.
Conclusions:
- The MPV17 protein is localized to peroxisomes, endosomes, and lysosomes, not mitochondria.
- This finding suggests a novel connection between peroxisomal/endosomal/lysosomal function and mitochondrial DNA depletion.
