The essential role of PP1 beta in Drosophila is to regulate nonmuscle myosin

N Vereshchagina, D Bennett, B Szoor, J Kirchner, S Gross, E Vissi, H White-Cooper, L Alphey*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Reversible phosphorylation of myosin regulatory light chain (MRLC) is a key regulatory mechanism controlling myosin activity and thus regulating the actin/myosin cytoskeleton. We show that Drosophila PP1beta, a specific isoform of serine/threonine protein phosphatase 1 (PP1), regulates nonmuscle myosin and that this is the essential role of PP1beta. Loss of PP1beta leads to increased levels of phosphorylated nonmuscle MRLC (Sqh) and actin disorganisation; these phenotypes can be suppressed by reducing the amount of active myosin. Drosophila has two nonmuscle myosin targeting subunits, one of which (MYPT-75D) resembles MYPT3, binds specifically to PP1beta, and activates PP1beta's Sqh phosphatase activity. Expression of a mutant form of MYPT-75D that is unable to bind PP1 results in elevation of Sqh phosphorylation in vivo and leads to phenotypes that can also be suppressed by reducing the amount of active myosin. The similarity between fly and human PP1beta and MYPT genes suggests this role may be conserved.

Original languageEnglish
Pages (from-to)4395-4405
Number of pages11
JournalMolecular Biology of the Cell
Volume15
Issue number10
DOIs
Publication statusPublished - Oct 2004

Keywords

  • PHOSPHATASE TYPE-1 PP1
  • PROTEIN PHOSPHATASE-1
  • LIGHT-CHAIN
  • PHOSPHORYLATION SITES
  • SMOOTH-MUSCLE
  • ACTIN
  • MORPHOGENESIS
  • TROPOMYOSIN
  • KINASE
  • GENE

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