TABLE 2.

Abl and Arg have similar enzymatic properties

Assay	Kinase	Substrate	Resultsa
			kcat (min−1)			Km (μM)			kcat/Km (min−1 μM−1)			Fold Δkcat/Kmb
			Nonact.	Autophos.	Hck Act.	Nonact.	Autophos.	Hck Act.	Nonact.	Auto.	Hck Act.	Auto.	Hck Act.
30 s	Abl	GST-Crk	0.07 ± 0.01	0.35 ± 0.05	0.8 ± 0.2	0.18 ± 0.05	0.20 ± 0.05	0.3 ± 0.2	0.39	1.75	2.7	4.5	6.9
	Arg	GST-Crk	0.04 ± 0.05	0.23 ± 0.02	0.5 ± 0.2	0.17 ± 0.1	0.15 ± 0.6	0.3 ± 0.2	0.25	1.53	1.7	6.1	6.6
5 min	Abl	GST-Crk	0.17 ± 0.02	0.33 ± 0.06	0.8 ± 0.2	0.19 ± 0.03	0.24 ± 0.04	0.5 ± 0.3	0.89	1.375	1.6	1.54	1.80
		GST-Crk(120-225)	0.09 ± 0.01	0.13 ± 0.01	ND	3.1 ± 0.2	2.9 ± 0.3	ND	0.029	0.045	ND	1.54	ND
		Peptidec	0.33 ± 0.06	0.65 ± 0.09	ND	27 ± 6	29 ± 1	ND	0.012	0.022	ND	1.83	ND
		ATPd	0.09 ± 0.01	ND	ND	0.9 ± 0.1	ND	ND	0.07	ND	ND	ND	ND
	Arg	GST-Crk	0.09 ± 0.01	0.22 ± 0.01	0.5 ± 0.1	0.24 ± 0.08	0.18 ± 0.01	0.5 ± 0.01	0.38	1.243	1.0	3.31	2.6
		GST-Crk(120-225)	0.06 ± 0.01	0.10 ± 0.01	ND	4.47 ± 0.08	6.0 ± 0.8	ND	0.013	0.017	ND	1.24	ND
		Peptidec	0.75 ± 0.08	1.10 ± 0.04	ND	123 ± 2	149 ± 8	ND	0.006	0.007	ND	1.21	ND
		ATPd	0.07 ± 0.01	ND	ND	0.7 ± 0.1	ND	ND	0.1	ND	ND	ND	ND

^aMean ± standard error; n = 4. ND, not determined; Act., activated; Autophos. or Auto., autophosphorylated.

^bn-Fold change in catalytic efficiency with autophosphorylation.

^cPeptide, AAVIYAAPFAKKK.

^dGST-Crk(120-225) as substrate.