TABLE 1. Kinetic parameters for FcαRI interactions with Fcα, mIgA1 κ, λ and Mce at 25° C.

Kinetic rate constants were determined using the bivalent ligand model in the program ClampXP.

Ligand	Analyte	k1on (M s)−1 a	k1off (s−1)	k2on (M s)−1	k2off (s−1) a	KD1 (nM)	KD2 (nM)
Fcα	FcαRI	4.61 × 105	0.0278	4.47 × 105	0.054	60.4 ± 0.3	121 ± 1
mIgA1κ b	FcαRI	3.55 × 105	0.0266	3.04 × 105	0.074	74.9 ± 0.4	244 ± 4
mIgA1λ	FcαRI	3.12 × 105	0.0254	5.25 × 105	0.102	81.5 ± 0.7	195 ± 6
mIgA1Mce	FcαRI	3.65 × 105	0.0264	4.56 × 105	0.101	72.3 ± 0.8	222 ± 8
mIgA1κ c	FcαRI	3.17 × 105	0.0267	3.15 × 105	0.096	84.1 ± 0.6	303 ± 8
Deglycosylated mIgA1κ c	FcαRI	3.29 × 105	0.0258	1.87 × 105	0.060	78.4 ± 0.6	320 ± 7

^aRate constants k1_on and k2_off have been corrected by statistical factors, as described in Experimental Procedures.

^bKinetic parameters for mIgA1κ listed here were derived from a global analysis of three independent experiments, each with eight different concentrations of injected analyte.

^cKinetic parameters for mIgA1κ before and after deglycosylation were determined from a single batch of mIgA1κ in order to more precisely determine the specific effects of glycosylation.