The cochlear F-box protein OCP1 associates with OCP2 and connexin 26

Michael T. Henzl, Isolde Thalmann, John D. Larson, Elena G. Ignatova, Ruediger Thalmann

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OCP1 and OCP2 are the most abundant proteins in the organ of Corti. Their distributions map identically to the epithelial gap-junction system, which unites the supporting cell population. Sequence data imply that OCP1 and OCP2 are subunits of an SCF E3 ubiquitin ligase. Consistent with that hypothesis, electrophoretic mobility-shift assays and pull-down assays with immobilized OCP1 demonstrate the formation of an OCP1-OCP2 complex. Sedimentation equilibrium data indicate that the complex is heterodimeric. The coincidence of the OCP1-OCP2 distribution and the epithelial gap-junction system suggests that one or more connexin isoforms may be targets of an SCFOCP1 complex. Significantly, immobilized OCP1 binds 35S-labeled connexin 26 (Cx26) produced by in vitro transcription-translation. Moreover, Cx26 can be co-immunoprecipitated from extracts of the organ of Corti by immobilized anti-OCP1, implying that OCP1 and Cx26 may associate in vivo. Given that lesions in the Cx26 gene (GJB2) are the most common cause of hereditary deafness, the OCP1-Cx26 interaction has substantial biomedical relevance.

Original languageEnglish
Pages (from-to)101-109
Number of pages9
JournalHearing research
Issue number1-2
StatePublished - May 2004


  • Ab, antibody
  • Cx, connexin
  • DEAE, diethylaminoethyl
  • DTT, dithiothreitol
  • EGJS, epithelial gap-junction system
  • EMSA, electrophoretic mobility shift assay
  • ESC, epithelial support complex
  • co-IP, co-immunoprecipitation
  • dpm, disintegrations per minute


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