TABLE 1.

Measurement of calcium binding to the high and low affinity calcium-binding sites of mCRT via isothermal titration calorimetry

Isothermal calorimetric binding data at 310.15 K (37 °C) for the calcium-binding sites for calreticulin.

Calcium binding site/mCRT construct	Starting [CaCl2]	[CaCl2] per injection	Calorimetric dataa
			K	ΔH	n	KD
	μm		mol−1	kJ/mol	mol	μm
High affinity site/mCRT(WT)	0	3.3	61236.4 ± 7494.3	−53.9 ± 12.2	0.8 ± 0.45	16.6 ± 2.0
High affinity site/mCRT(1–339)	0	1.7 and 3.3	74101 ± 6962.9	−109.2 ± 25.2	0.45 ± 0.25	13.6 ± 1.3
High affinity site/mCRT(ΔP)	0	1.7	44251.99 ± 901.7	−84.15 ± 34.6	0.48 ± 0.23	22.6 ± 0.5
High affinity site/mCRT(D311A)	0	3.3	NDb	ND	ND	ND
High affinity site/mCRT(1–339) + 1 mm MgCl2	0	1.7	ND	ND	ND	ND
High capacity, low affinity sites/mCRT(WT)	50	33	1786.5 ± 312.7	9.8 ± 0.4	3.8 ± 0.5	590.6 ± 88.0
High capacity, low affinity sites/mCRT(1–339)	50	33	ND	ND	ND	ND
High capacity, low affinity sites/mCRT(D311A)	50	33	2319.2 ± 273.7	10.8 ± 3.0	3.8 ± 0.2	437.3 ± 51.6
High capacity, low affinity sites/mCRT(1–351)	50	33	1514.8 ± 65.3	4.6 ± 0.7	2.1 ± 0.03	661.4 ± 28.5
High capacity, low affinity sites/mCRT(1–362)	50	33	1976.5 ± 90.8	3.9 ± 0.4	5.9 ± 1.1	507.0 ± 23.3
High capacity, low affinity sites/mCRT(WT) + 1 mm MgCl2	50	33	166.7 ± 5.1	86.8 ± 4.9	1.04 ± 0.06	6003.6 ± 184.5

^a Data represent mean ± S.E. for at least two replicates.

^b ND, no detectable binding.