The Small β-Barrel Domain: A Survey-Based Structural Analysis

Philippe Youkharibache, Stella Veretnik, Qingliang Li, Kimberly A. Stanek, Cameron Mura, Philip E. Bourne

Research output: Contribution to journalReview articlepeer-review

30 Scopus citations


The small β-barrel (SBB) is an ancient protein structural domain characterized by extremes: it features a broad range of structural varieties, a deeply intricate evolutionary history, and it is associated with a bewildering array of cellular pathways. Here, we present a thorough, survey-based analysis of the structural properties of SBBs. We first consider the defining properties of the SBB, including various systems of nomenclature used to describe it, and we introduce the unifying concept of an “urfold.” To begin elucidating how vast functional diversity can be achieved by a relatively simple domain, we explore the anatomy of the SBB and its representative structural variants. Many SBB proteins assemble into cyclic oligomers as the biologically functional units; these oligomers often bind RNA, and typically exhibit great quaternary structural plasticity (homomeric and heteromeric rings, variable subunit stoichiometries, etc.). We conclude with three themes that emerge from the rich structure ↔ function versatility of the SBB.

Original languageEnglish
Pages (from-to)6-26
Number of pages21
Issue number1
StatePublished - Jan 2 2019


  • OB
  • RNA-binding protein
  • RRM
  • SH3
  • Sm/Hfq
  • oligomer
  • protein evolution
  • structural bioinformatics
  • structure/function relationship
  • superfold
  • β-barrel
  • β-sheet


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