Fig. 4.

The STPK interacting proteins were also the substrates of the corresponding kinase. Phosphorylation reactions were carried out by adding both the STPKs and the purified interacting proteins. Four representative STPKs, i.e. PknB, PknD, PknG and PknH were included, the phosphorylation reactions were performed with 2 randomly selected interacting proteins for each of the STPK. Reactions without ATP were also included as negative controls. The proteins were then subjected for mass spectrometry analysis to determine the phosphorylated serine/threonine sites.