Evolution of the Cdk-activator Speedy/RINGO in vertebrates

Research output: Contribution to journalArticle


Successful completion of the cell cycle relies on the precise activation and inactivation of cyclindependent kinases (Cdks) whose activity is mainly regulated by binding to cyclins. Recently, a new family of Cdk regulators termed Speedy/RINGO has been discovered, which can bind and activate Cdks but shares no apparent amino acid sequence homology with cyclins. All Speedy proteins share a conserved domain of approximately 140 amino acids called ''Speedy Box'', which is essential for Cdk binding. Speedy/RINGO proteins display an important role in oocyte maturation in Xenopus. Interestingly, a common feature of all Speedy genes is their predominant expression in testis suggesting that meiotic functions may be the most important physiological feature of Speedy genes. Speedy homologs have been reported in mammals and can be traced back to the most primitive clade of chordates (Ciona intestinalis). Here, we investigated the evolution of the Speedy genes and have identified a number of new Speedy/RINGO proteins. Through extensive analysis of numerous species, we discovered diverse evolutionary histories: the number of Speedy genes varies considerably among species, with evidence of substantial gains and losses. Despite the interspecies variation, Speedy is conserved among most species examined. Our results provide a complete picture of the Speedy gene family and its evolution.


  • Sangeeta Chauhan
  • Xinde Zheng
  • Yue Ying Tan
  • Boon Hui Tay
  • Shuhui Lim
  • Byrappa Venkatesh
  • Philipp Kaldis
External organisations
  • National University of Singapore
  • A*Star Institute of Molecular and Cell Biology (IMCB)
Original languageEnglish
Pages (from-to)3835-3850
JournalCellular and Molecular Life Sciences
Issue number22
Publication statusPublished - 2012 Nov 1
Publication categoryResearch
Externally publishedYes