Structure, processing and properties of surfactant protein A.

Surfactant protein A (SP-A) is a highly ordered, oligomeric glycoprotein that is secreted into the airspaces of the lung by the pulmonary epithelium. The in vitro activities of protein suggest diverse roles in pulmonary host defense and surfactant homeostasis, structure and surface activity. Functional mapping of SP-A using directed mutagenesis has identified domains which interact with surfactant phospholipids, alveolar type II cells and microbes. Recently developed genetically manipulated animal models are beginning to clarify the critical physiological roles for SP-A in the normal lung, and in the pathophysiology of pulmonary disease.