A misassembled transmembrane domain of a polytopic protein associates with signal peptide peptidase

Biochem J. 2004 Nov 15;384(Pt 1):9-17. doi: 10.1042/BJ20041216.


The endoplasmic reticulum (ER) exerts a quality control over newly synthesized proteins and a variety of components have been implicated in the specific recognition of aberrant or misfolded polypeptides. We have exploited a site-specific cross-linking approach to search for novel ER components that may specifically recognize the misassembled transmembrane domains present in truncated polytopic proteins. We find that a single probe located in the transmembrane domain of a truncated opsin fragment is cross-linked to several ER proteins. These components are distinct from subunits of the Sec61 complex and represent a 'post-translocon' environment. In this study, we identify one of these post-translocon cross-linking partners as the signal peptide peptidase (SPP). We find that the interaction of truncated opsin chains with SPP is mediated by its second transmembrane domain, and propose that this interaction may contribute to the recognition of misassembled transmembrane domains during membrane protein quality control at the ER.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / genetics
  • Animals
  • Aspartic Acid Endopeptidases / antagonists & inhibitors
  • Aspartic Acid Endopeptidases / metabolism*
  • Cattle
  • Cross-Linking Reagents / metabolism
  • Dipeptides / pharmacology
  • Endoplasmic Reticulum / metabolism
  • Enzyme Inhibitors / pharmacology
  • Intracellular Membranes / chemistry
  • Membrane Proteins / metabolism
  • Molecular Probes
  • Peptides / chemistry
  • Peptides / metabolism
  • Protein Folding
  • Protein Structure, Tertiary
  • Rod Opsins / genetics
  • Rod Opsins / metabolism*


  • 1, 3-di-(N-carboxybenzoyl-leucyl-leucyl)amino acetone
  • Cross-Linking Reagents
  • Dipeptides
  • Enzyme Inhibitors
  • Membrane Proteins
  • Molecular Probes
  • Peptides
  • Rod Opsins
  • Aspartic Acid Endopeptidases
  • signal peptide peptidase