Phosphorylation ends up shifting all over the place?

Ummm....
If this was coming out of other labs, maybe I would glaze right over and by this.  But this is coming out of Karl Mechtler's lab.  Backing up....  A paper in this month's Proteomics (Wiley) from Andreas Schmidt et al., examines arginine phosphorylation using a global approach.  Arginine phosphorylation in bacteria is something that just exploded last year, with a couple really nice papers on where/how it works in Bacillus subtilis.  In this paper, this group looks very closely at this and other phosphorylation sites and shows what appears to be phospho groups jumping all over the place during LC-MS/MS analysis.  I would have glazed over this because I recall this being a topic of conversation about 6 years ago, phosphorylations moving around during fragmentation, but there was some solid contradictory evidence and we all moved on.
 And here it is again.  Just when we think we've got a system figured out.  If you are doing any kind of phosphorylation analysis this is worth a read.  If you are one of the many groups tracking arginine phosphorylation in bacteria (or mammals!?!?) definitely jump on this.