Multiple serine phosphorylation sites on the 30 kDa TMV cell-to-cell movement protein synthesized in tobacco protoplasts

Plant J. 1995 Nov;8(5):715-24. doi: 10.1046/j.1365-313x.1995.08050715.x.


p30, the protein required for cell-to-cell movement of tobacco mosaic virus (TMV), has a slightly reduced mobility on SDS-polyacrylamide gels when isolated by immunoprecipitation from TMV-infected protoplasts compared with that of p30 translated from viral RNA in vitro. Further investigation established a probable cause for the difference in mobility between the two: protoplasts incorporate [32P]orthophosphate into p30 at multiple sites, predominantly as phosphoserine. Tryptic peptide mapping reveals at least five internal phosphopeptides in p30, besides the C-terminal tryptic phosphopeptide already reported, involving at least two distinct domains of the protein (at residues 61-114 and residues 212-231), which may be substrates for different protein kinases. These structural results are consistent with a three-domain model for the TMV movement protein with two regulatory domains similar to that recently proposed on genetic grounds for dianthovirus movement proteins.

Publication types

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

MeSH terms

  • Peptide Mapping
  • Phosphoproteins / biosynthesis*
  • Phosphorylation
  • Phosphoserine / analysis*
  • Plant Viral Movement Proteins
  • Plants, Toxic*
  • Protoplasts / virology
  • Tobacco / virology*
  • Tobacco Mosaic Virus / metabolism*
  • Viral Proteins / biosynthesis*


  • Phosphoproteins
  • Plant Viral Movement Proteins
  • Viral Proteins
  • Phosphoserine