Table I

A comparison of different proteomic strategies for measuring protein phosphorylation

Analytical methodPhosphorylated amino acids detectedQuantitativeSite of phosphorylation identifiedGeneral comments
Conventional methods
32P radiolabelingSer, Thr, TyrSemiDifficultRequires living samples
 Phospho-specific antibodiesSer, Thr, TyrNoDifficultHigh nonspecific binding
 IMACSer, Thr, TyrYes (d0 or d3 methanol)DifficultMethylation of carboxylic acids reduces backgrounda
Chemical methods
 β-EliminationbSer, ThrYes (d0 or d4 ethanedithiol)Yes (tag survives MS/MS)Potential for β-elimination of O-linked carbohydrates
 PhosphoramidatecSer, Thr, TyrYes (d0 or d4 ethanolamine)DifficultLengthy protocol
  • a See Ref. 25.

  • b See Refs. 26 and 27.

  • c See Ref. 28.