Crk proteins activate the Rap1 guanine nucleotide exchange factor C3G by segregated adaptor-dependent and -independent mechanisms

Table 1 Parameters of dose-response activation of C3G by Crk proteins

C3G	Crk protein	AC₅₀ (µM)^a	k_free x1000 (s⁻¹ µM⁻¹)	k_max x1000 (s⁻¹ µM⁻¹)	k_max/k_free
C3G	CrkL	22.4 ± 4.5	1.7 ± 0.4	13.4 ± 0.6	7.9 ± 2.1
C3G-AAPP	CrkL	23.7 ± 6.6	2.4 ± 0.5	13.6 ± 0.8	5.7 ± 1.2
C3G-AAPA	CrkL	28.1 ± 5.7	2.1 ± 0.2	9.1 ± 0.4	4.3 ± 0.5
C3G	CrkL-SH3N	26.8 ± 6.5	1.5 ± 0.1	6.3 ± 0.4	4.2 ± 0.4
C3G	CrkL-SH2-SH3N	15.8 ± 2.6	1.2 ± 0.2	8.4 ± 0.2	7.0 ± 1.3
C3G	CrkL-SH3N-SH3C	19.8 ± 3.9	1.6 ± 0.3	12.9 ± 0.6	8.1 ± 1.7
C3G	CrkII	65.7 ± 20.4	1.6 ± 0.2	7.2 ± 0.5	4.5 ± 0.7
C3G	CrkL-II-L	16.7 ± 4.5	0.9 ± 0.3	7.9 ± 0.3	8.8 ± 3.4
C3G	CrkII-L-II	18.7 ± 2.4	1.2 ± 0.1	7.9 ± 0.2	6.6 ± 0.8
pC3G	CrkL	1.7 ± 0.2	2.3 ± 0.6	34.2 ± 1.0	14.9 ± 4.0
pC3G-AAPP	CrkL	2.2 ± 0.5	3.3 ± 1.0	35.7 ± 2.0	10.8 ± 3.3
pC3G-AAPA	CrkL	1.3 ± 0.3	6.2 ± 0.9	26.9 ± 0.8	4.3 ± 0.6
pC3G-AAAP	CrkL	0.6 ± 0.6	2.9 ± 0.4	4.5 ± 0.2	1.6 ± 0.2
pC3G	CrkL-SH3N	12.8 ± 4.6	2.9 ± 0.5	13.9 ± 1.2	4.8 ± 0.9
pC3G	CrkL-SH2-SH3N	4.9 ± 0.8	2.5 ± 0.8	37.7 ± 1.5	15.1 ± 4.6
pC3G	CrkL-SH3N-SH3C	4.5 ± 1.0	3.7 ± 0.4	13.4 ± 0.4	3.6 ± 0.4
pC3G	CrkII	2.6 ± 0.6	2.1 ± 0.8	22.3 ± 0.9	10.6 ± 4.2
pC3G	CrkL-II-L	2.3 ± 0.5	2.2 ± 1.3	33.6 ± 1.2	15.3 ± 8.5
pC3G	CrkII-L-II	1.6 ± 0.4	2.4 ± 1.6	30.0 ± 0.9	12.5 ± 8.5

^aParameters are presented as the fitted value ± the associated standard errors of the nonlinear regression fit

ISSN: 1478-811X