how to find the modification enzyme of a target protein - (Jul/31/2008 )

If my interesting appear to be modified like phospholated, how can I get the enzyme which catalyze it? what about use the GST-recombinant target protein as bait?
thanks!

---

if your protein of interest has multiple phosphorylation sites, various protein kinases may be involved; check for phosphorylation site motifs to get some candidates; however, there will be numerous exceptions from motif-related phosphorylation; you may start with candidate protein kinases to phosphorylate your protein in vitro

---