Table 2

The effect of SCH 28080, inorganic phosphate, vanadate, and K⁺on the steady-state ATP phosphorylation level

ATP phosphorylation capacity (pmol P · mg⁻¹)
	Control	SCH 28080	Pi	Pi SCH 28080	Vanadate	KCl
wild-type	4.06 ± 0.56	0.01 ± 0.25^**	1.40 ± 0.28^*	−0.09 ± 0.14^**	−0.05 ± 0.08^**	0.06 ± 0.28^**
E820D	3.67 ± 0.04	0.33 ± 0.08^**	1.39 ± 0.19^**	0.16 ± 0.08^**	0.07 ± 0.18^**	0.23 ± 0.07^**
E820Q	2.86 ± 0.22	6.27 ± 0.44^**	2.65 ± 0.11	3.66 ± 0.43	1.49 ± 0.10^**	1.60 ± 0.16^**
E820N	3.94 ± 0.25	1.65 ± 0.64^*	3.21 ± 0.25	0.11 ± 0.27^**	0.10 ± 0.10^**	2.65 ± 0.28^*
E820A	5.38 ± 1.66	4.02 ± 1.61	4.80 ± 1.44	0.55 ± 0.36^*	4.11 ± 1.02	4.20 ± 1.12

Sf9 membranes (4–8 μg) were preincubated in the presence of 50 mM Tris-acetic acid (pH 6.0), 1.2 mM MgCl₂, 0.2 mM EDTA, and in addition with either 0.1 mM SCH 28080, 1 mM inorganic phosphate pH 6.0 (Pi), 0.1 mM SCH 28080 + 1.0 mM Pi, 1 mM vanadate, or 10 mM KCl at 21°C. After 60 min 0.1 μM [γ-³²P]ATP (final concentration) was added and after 10 s the amount of E–P was determined. The data are corrected for the levels obtained with membranes of mock infected Sf9 cells. Averages with S.E.M. for three enzyme preparations are presented. Differences of the data compared to the control values are tested for significance by means of Student’st test (^*p < .05; ^**p < .01).