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Updated: May 22, 2026
10:09
Detection of Detergent-sensitive Interactions Between Membrane Proteins
Published on: March 7, 2018
Vigilin interacts with signal peptide peptidase
Stephen Hsueh-Jeng Lu1, Amy Hye Won Jeon, Gerold Schmitt-Ulms
1Cambridge Institute for Medical Research, Department of Clinical Neurosciences, University of Cambridge, Addenbrooke's Hospital, Hills Road, England, Cambridge, CB2 0XY, United Kingdom. phs22@cam.ac.uk.
Proteome Science
|May 22, 2012
Summary
Signal peptide peptidase (SPP) interacts with vigilin, a protein involved in RNA binding. This interaction may support SPP's non-proteolytic functions in the endoplasmic reticulum (ER).
Area of Science:
- Cell Biology
- Molecular Biology
- Proteomics
Background:
- Signal peptide peptidase (SPP) is an aspartyl protease involved in endoplasmic reticulum (ER) functions.
- SPP exists in high molecular weight complexes (100-450 kDa) suggesting regulatory or non-catalytic roles.
- SPP is implicated in MHC Class I retro-translocation and binding misfolded proteins.
Purpose of the Study:
- To identify proteins interacting with SPP using an unbiased mass spectrometry approach.
- To investigate the functional significance of SPP-interacting proteins in SPP's non-proteolytic functions.
Main Methods:
- iTRAQ-labeling mass spectrometry for protein identification.
- Blue Native (BN) gel electrophoresis to analyze protein complexes.
- Immunofluorescence microscopy for co-localization studies.
- Biochemical fractionation to assess co-purification.
Main Results:
- Vigilin, an RNA-binding protein, was identified as a selective SPP-interacting partner.
- SPP and vigilin co-localized near the ER and co-fractionated biochemically.
- Vigilin was found within the 450 kDa SPP complex on BN gels.
- Vigilin did not affect SPP's protease activity, suggesting a role in non-proteolytic functions.
Conclusions:
- Vigilin is a novel interacting partner of SPP.
- The SPP-vigilin interaction likely contributes to SPP's non-proteolytic functions.
- Intramembrane-cleaving aspartyl proteases like SPP may possess functions beyond proteolysis.
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