TABLE 1.

Kinetic data for human CD200 and HHV-8 K14 proteins binding human, rat and mouse CD200R^a

CD200R	KD (μM)		koff
	Host CD200	Viral K14	Host CD200		Viral K14
			s−1	t1/2 (s)	s−1	t1/2 (s)
Human	0.49 ± 0.08	0.49 ± 0.09	0.09 ± 0.004	7.7	0.11 ± 0.008	6.1
Rat	0.59 ± 0.07	0.67 ± 0.07	0.24 ± 0.03	2.9	0.17 ± 0.03	4.1
Mouse	7.0 ± 0.33	9.2 ± 0.98	2.10 ± 0.2	0.3	1.7 ± 0.3	0.4

^aThe K_D values were determined by averaging those calculated from each of the three different CD200R immobilization levels obtained by nonlinear curve fitting (note that the curves shown in Fig. 2B are from high levels of human CD200R immobilization alone). The k_off values were determined by averaging the values obtained by fitting the dissociation phases of the binding curves to a simple 1:1 binding model (see Materials and Methods), using two different concentrations of ligand over three levels of receptor immobilization (i.e., n = 6). In all cases, the level of receptor immobilization had negligible effects on k_off, indicating that mass transport and rebinding effects were minimal. Data for CD200-CD200R interaction are from reference 42. Results are shown as means ± standard deviations.