Table 1.

Molar Partition Coefficients, K, for the Ca²⁺-dependent and Ca²⁺-independent membrane affinity of the syt1 C2 domains.^†

POPC:POPS (3:1)	Syt1C2A	Syt1C2B	Syt1C2AB
[Ca2+]=1 mM	1.1 (± 0.1) × 103	6.9 (± 0.1) × 103	5.3 (± 1.0) × 103
No Ca2+	Not detected	2.9 (± 0.3) × 102	1.2 (± 0.1) × 102

^†Values of K are give in units of M⁻¹. The errors represent the uncertainty obtained from the non-linear regression procedure used in the fitting the data to K. Samples in the Ca²⁺-free state contained 2 to 5 mM EGTA. The reciprocal of K corresponds to the accessible molar lipid concentration at which 50% of the protein is membrane bound.