Km Values for ATP and Peptide Substrate for Near-Full-Length SFKs.

The Km values for ATP and the substrate peptide, YIYGSFK, were determined for each SFK-YEEI protein using the ADP Quest assay as described under Materials and Methods. ATP experiments were performed three times for each kinase and substrate experiments were performed four times for each kinase, except for Src-YEEI, where ATP experiments were performed twice and substrate experiments were performed three times. Mean values are shown for each kinetic constant ±S.E.