A modified His-tag vector for the production of recombinant protein kinases.

Histidine-tag (His-tag) is the most frequently used tag to label and purify recombinant protein kinases, namely autokinases. However, when analyzing protein phosphorylation, it appears that this modification occurs not only on the kinase itself but also on several serine residues present in the vector-derived His-tag sequence. These parasite modifications can thus lead to misinterpretation of the data concerning protein phosphorylation. We report here on a modified vector devoid of serine residues in the tag and, therefore, more appropriate and secure for studying protein phosphorylation.