Recently discovered PTM may be surprisingly common.

O-GlcNAc-6-phosphate is a recently discovered PTM that was previously only identified on a single protein found in rat neurons.  A paper this month in MCP from Hannes Hahne and Bernard Kuster demonstrates that this modification is a whole lot more common.  By tracing specific reporter ions produced by the degradation of the mod during CID, they were able to confirm the presence of this modification on a number of different mouse neuronal proteins.  They also confirm that this modification is found on some human proteins.