The lung lectin surfactant protein A aggregates phospholipid vesicles via a novel mechanism.

Surfactant protein A (SP-A), a lung-specific glycoprotein, consists of an N-terminal collagen-like domain and a C-terminal domain with a sequence similar to that of several Ca2(+)-dependent lectins. SP-A induces a rapid Ca2(+)-dependent aggregation of phospholipid vesicles. We report here that vesicle aggregation is mediated by Ca2(+)-induced interactions between carbohydrate-binding domains and oligosaccharide moieties of SP-A.

Surfactant protein composition of lamellar bodies isolated from rat lung.

Lamellar bodies isolated from rat lung contain all three classes of surfactant proteins, SP-A, SP-B and SP-C, as determined by immunoblot analysis. The amounts of the surfactant proteins present in lamellar bodies, determined by sandwich e.l.