CK1δ and CK1ε are components of human 40S subunit precursors required for cytoplasmic 40S maturation

J Cell Sci. 2014 Mar 15;127(Pt 6):1242-53. doi: 10.1242/jcs.138719. Epub 2014 Jan 14.


Biogenesis of 40S pre-ribosomal subunits requires many trans-acting factors, among them several protein kinases. In this study, we show that the human casein kinase 1 (CK1) isoforms δ and ε are required for cytoplasmic maturation steps of 40S subunit precursors. We show that both CK1δ and CK1ε isoforms are components of pre-40S subunits, on which they phosphorylate the ribosome biogenesis factors ENP1/BYSL and LTV1. Inhibition or co-depletion of CK1δ and CK1ε results in failure to recycle a series of trans-acting factors including ENP1/BYSL, LTV1, RRP12, DIM2/PNO1, RIO2 and NOB1 from pre-40S particles after nuclear export. Furthermore, co-depletion of CK1δ and CK1ε leads to defects in 18S-E pre-rRNA processing. Together, these data demonstrate that CK1δ and CK1ε play a decisive role in triggering late steps of pre-40S maturation that are required for acquisition of functionality of 40S ribosomal subunits in protein translation.

Keywords: CK1δ; CK1ε; Pre-40S maturation; Protein kinase; Ribosome biogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Casein Kinase 1 epsilon / metabolism*
  • Casein Kinase Idelta / metabolism*
  • Cell Adhesion Molecules / metabolism
  • Cytoplasm / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Phosphorylation
  • Protein Precursors / metabolism*
  • Protein Processing, Post-Translational
  • Protein Subunits / metabolism*
  • Protein Transport
  • RNA, Ribosomal / metabolism
  • Ribosome Subunits, Small, Eukaryotic / metabolism*
  • Trans-Activators / metabolism


  • BYSL protein, human
  • Cell Adhesion Molecules
  • Protein Precursors
  • Protein Subunits
  • RNA, Ribosomal
  • Trans-Activators
  • Casein Kinase 1 epsilon
  • Casein Kinase Idelta