Table 2.

Parameter estimates from Hill fits to velocity-pCa data for the effect of P_i

pH	Pi	pCa50	Hill	R2
7.4	0	6.71 ± 0.07	2.02 ± 0.37	0.86
	15	6.75 ± 0.04	1.83 ± 0.33	0.90
6.8	0	6.71 ± 0.07	1.76 ± 0.45	0.83
	15	6.34 ± 0.26	1.49 ± 0.46	0.81
6.5	0	4.55 ± 0.24*	4.57 ± 12.1	0.22
	15	6.24 ± 0.18†	1.32 ± 0.63	0.67

Values represent means ± SE for filaments reconstituted with WT Tn.

^*Significantly different from pH 7.4 and 0 mM inorganic phosphate (P_i). †Significantly different from 0 mM P_i at pH 6.5.