Abstract
Src and Abl are two tyrosine kinases that have similar structures but different activation and inhibition mechanisms. Previous studies and crystal structures have given insight on the structures of Abl and Src which include information on vital tyrosine residues, regulatory domains and myristoyl groups. In order to investigate these regulatory mechanisms and their evolution over time, we reconstructed a common ancestor of Src and Abl and the common ancestors between Abl/Src and the Tec and Fer families of kinases. We wanted to create a methodology to examine the evolution of kinase regulation not only qualitatively, but also quantitatively. We started with the well-known Src and Abl, and compared their abilities to autophosphorylate and their rates of activity via a kinetic assay that measured kcat, the number of conversions of substrate molecule per second by a single active site. We manipulated different regulatory elements, so that we could investigate the differential modes of regulation of these kinases. Once these methods were well developed, we repeated them on early ancestors of Src and Abl, so that we could study how regulation had evolved over time.