Site-specific and temporally-regulated retinoblastoma protein dephosphorylation by protein phosphatase type 1

Oncogene. 2001 Jun 28;20(29):3776-85. doi: 10.1038/sj.onc.1204518.


pRb is dephosphorylated at mitotic exit by the type 1 serine/threonine protein phosphatases (PP1). Here we demonstrate for the first time that mitotic pRb dephosphorylation is a sequential, temporally-regulated event. We also provide evidence that the three mammalian isoforms of PP1, alpha, gamma-1, and delta, differ in their respective preferences for site-specific pRb dephosphorylation and that the mitotic and G(1) PP1-isoform counterparts exhibit differential activities towards mitotic pRb. Finally, the physiological relevance of the striking contrast between the patterns of Thr821 and Thr826 dephosphorylation, sites known to be important for disrupting binding of LXCXE-containing proteins to pRb, is addressed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • Cell Line
  • Chlorocebus aethiops
  • G1 Phase
  • Isoenzymes / metabolism
  • Mitosis / physiology
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Retinoblastoma Protein / metabolism*
  • Threonine / metabolism


  • Isoenzymes
  • Retinoblastoma Protein
  • Threonine
  • Phosphoprotein Phosphatases