Phosphorylation influences water and ion channel function of AtPIP2;1

Plant Cell Environ. 2020 Oct;43(10):2428-2442. doi: 10.1111/pce.13851. Epub 2020 Aug 17.


The phosphorylation state of two serine residues within the C-terminal domain of AtPIP2;1 (S280, S283) regulates its plasma membrane localization in response to salt and osmotic stress. Here, we investigated whether the phosphorylation state of S280 and S283 also influence AtPIP2;1 facilitated water and cation transport. A series of single and double S280 and S283 phosphomimic and phosphonull AtPIP2;1 mutants were tested in heterologous systems. In Xenopus laevis oocytes, phosphomimic mutants AtPIP2;1 S280D, S283D, and S280D/S283D had significantly greater ion conductance for Na+ and K+ , whereas the S280A single phosphonull mutant had greater water permeability. We observed a phosphorylation-dependent inverse relationship between AtPIP2;1 water and ion transport with a 10-fold change in both. The results revealed that phosphorylation of S280 and S283 influences the preferential facilitation of ion or water transport by AtPIP2;1. The results also hint that other regulatory sites play roles that are yet to be elucidated. Expression of the AtPIP2;1 phosphorylation mutants in Saccharomyces cerevisiae confirmed that phosphorylation influences plasma membrane localization, and revealed higher Na+ accumulation for S280A and S283D mutants. Collectively, the results show that phosphorylation in the C-terminal domain of AtPIP2;1 influences its subcellular localization and cation transport capacity.

Keywords: Arabidopsis; NSCC; aquaporin; gating; osmotic stress; potassium; regulation; salt stress; sodium transport; trafficking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Aquaporins / metabolism*
  • Aquaporins / physiology
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Arabidopsis Proteins / physiology
  • Ion Channels / metabolism*
  • Oocytes
  • Phosphorylation
  • Water / metabolism
  • Xenopus laevis


  • Aquaporins
  • Arabidopsis Proteins
  • Ion Channels
  • plasma membrane intrinsic protein 2 Arabidopsis
  • Water