Protein modifications or post-translational modifications (PTMs) are chemical changes to proteins after translation which often influence the protein's function, activity, and/or fate [x]. Examples of PTMs include the addition of phosphates, ubiquitin and methyl groups on proteins by specific enzymes.
Fig. 1
Different types of PTM to proteins.
http://www.nature.com/nrg/journal/v14/n7/images/nrg3462-f3.jpg
Post-translational modifications of NKX2-5
The NKX2-5 homeobox transcription factor is modified post-translationally via phosphate addition at several sites along its amino acid sequence. According to NetPhos, there are
Fig 2. Predicted phosphate additions at Ser, Thr, and Tyr. Graph was generated using NetPhos 3.1. http://www.cbs.dtu.dk/cgi-bin/webface2.fcgi?jobid=58CAF25000007D2756DB7F82&wait=20