Fig. 9.

The calcium-dependent binding of SP-A is inhibited by P63 Ab. Type II cells were incubated in HBSS without or with calcium (1 mM). Anti-P63 or nonimmune IgG was added for 15 min followed by the addition of ¹²⁵I-SP-A (0.5 μg/ml) for 1 h at 4°C. The cells were harvested, and the calcium-dependent binding was determined by subtracting the binding in the absence of calcium (calcium-independent) from the total binding (with calcium). Data are the means ± SE (n = 3) expressed as a percentage of total binding with calcium (Control). Control = 111 ± 31 ng ¹²⁵I-SP-A/mg cell protein. *Statistically significant difference from binding without additions or with IgG. P < 0.05.