Comparison of lipid aggregation and self-aggregation activities of pulmonary surfactant-associated protein A.

1. We compared the Ca2+ dependence of the self-aggregation of surfactant protein A (SP-A) with that of vesicle aggregation induced by SP-A. The Ca2+ concentration required for half-maximal activity of lipid aggregation was 0.74 +/- 0.29 microM (n = 4) for pig SP-A and 98 +/- 5 microM (n = 2) for dog SP-A. In contrast, the threshold concentration of Ca2… (More)