Single-molecule approach to immunoprecipitated protein complexes: Insights into miRNA uridylation

Kyu Hyeon Yeom, Inha Heo, Jinwoo Lee, Sungchul Hohng, V. Narry Kim, Chirlmin Joo

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


Single-molecule techniques have been used for only a subset of biological problems because of difficulties in studying proteins that require cofactors or post-translational modifications. Here, we present a new method integrating single-molecule fluorescence microscopy and immunopurification to study protein complexes. We used this method to investigate Lin28-mediated microRNA uridylation by TUT4 (terminal uridylyl transferase 4, polyU polymerase), which regulates let-7 microRNA biogenesis. Our real-time analysis of the uridylation by the TUT4 immunoprecipitates suggests that Lin28 functions as a processivity factor of TUT4. Our new technique, SIMPlex (single-molecule approach to immunoprecipitated protein complexes), provides a universal tool to analyse complex proteins at the single-molecule level.

Original languageEnglish
Pages (from-to)690-696
Number of pages7
JournalEMBO Reports
Issue number7
StatePublished - Jul 2011


  • Lin28 (Lin28a
  • Lin28)
  • Lin28b
  • TUT4 (ZCCHC11)
  • real-time hybridization
  • single-molecule fluorescence
  • single-molecule immunoprecipitation


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