Deletional analysis of the rod photoreceptor cell peripherin/RDS carboxy-terminal region

Exp Eye Res. 2002 Aug;75(2):143-54. doi: 10.1006/exer.2002.2013.


The C-terminal region of peripherin/rds contains three predicted alpha-helical domains. One of these domains, corresponding to amino acids 311-322, form an amphiphilic alpha-helix previously shown to promote membrane fusion. The present studies were conducted to determine how the additional alpha-helical regions of the peripherin/rds C-terminus affect complex formation with rom-1, glycosylation, intracellular localization and membrane fusion properties. Bovine peripherin/rds and rom-1 were epitope tagged with an amino-terminal FLAG-tag or amino-terminal hemagglutinin (HA)-tag, respectively, and cloned into the pCI-neo expression vector for transient transfection into COS cells. Similarly, four C-terminal peripherin/rds truncation mutants (Delta1, Delta2, Delta3 and Delta4), corresponding to deletions of -19, -29, -39 and -59 amino acids were designed to disrupt the alpha-helical domains. Immunofluorescence microscopy and enzymatic digestions demonstrated that full-length peripherin/rds and the four C-terminal deletion mutants were localized to intracellular membranes and were all Endo-H sensitive. Western blotting and immunoprecipitation studies showed that the FLAG-tagged bovine peripherin/rds (full-length) was expressed as a 76kDa dimer, which associates with HA-tagged rom-1 to form a higher order complex. The deletion mutants were also able to associate with rom-1. However, when analyzed using non-denaturing tricine electrophoresis, full-length peripherin/rds and the Delta1, Delta2 and Delta3 mutants formed homo-oligomeric complexes, while the Delta4 mutant appeared to form only homodimers suggesting a region upstream of amino acid 300 may be involved in C-terminal interactions. Membrane fusion was then evaluated using fluorescence resonance energy transfer (RET) techniques. Intracellular COS cell membranes containing full-length peripherin/rds fused with rod outer segment plasma membrane vesicles. This fusion was inhibited with the addition of a synthetic peptide (PP-5) corresponding to the fusion domain of peripherin/rds. In contrast, fusion was negligible with any of the C-terminal truncation mutants. Collectively, these results suggest that in addition to the fusion domain, other regions of the peripherin/rds C-terminus are required for fusion. Most interesting is the observation that the last 19amino acids, a region downstream of the fusion peptide that is deleted in the Delta1 mutant, appear to be necessary for fusion. This region corresponds to the epitope for anti-peripherin/rds monoclonal antibody 2B6, which is shown to partially inhibit peripherin/rds mediated membrane fusion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Western
  • Cattle
  • Electrophoresis, Polyacrylamide Gel
  • Eye Proteins / genetics
  • Gene Deletion
  • Glycosylation
  • Intermediate Filament Proteins / genetics*
  • Membrane Fusion / genetics
  • Membrane Glycoproteins / genetics
  • Membrane Proteins / genetics
  • Mice
  • Mice, Inbred Strains
  • Mutation
  • Nerve Tissue Proteins / genetics*
  • Peripherins
  • Precipitin Tests
  • Retinal Degeneration / genetics*
  • Retinal Rod Photoreceptor Cells / physiopathology*
  • Rod Cell Outer Segment / physiopathology
  • Tetraspanins


  • Eye Proteins
  • Intermediate Filament Proteins
  • Membrane Glycoproteins
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Peripherins
  • Prph2 protein, mouse
  • Rom1 protein, mouse
  • Tetraspanins