TABLE 1.

K_D values and concentrations of binding sites (R_t) for Cry1 toxins binding to BBMV proteins from H. armigera, H. zea, and S. exigua, determined using Cry1Ac as the labeled ligand^a

Toxin	H. armigera		H. zea		S. exigua
	KD (nM) ± SD	Rt (pmol/ mg protein) ± SD	KD (nM) ± SD	Rt (pmol/ mg protein) ± SD	KD (nM) ± SD	Rt (pmol/ mg protein) ± SD
Cry1Ac	1.6 ± 0.2	16.4 ± 0.2	0.34 ± 0.04	29.6 ± 0.5	0.7 ± 0.5	4.6 ± 0.5
Cry1Fa	150 ± 40		220 ± 10		29 ± 7
Cry1Ja	250 ± 20		640 ± 2		22 ± 2

^aK_D values of heterologous ligands are estimated assuming an R_t the same as that for the labeled ligand.