Structure of canine pulmonary surfactant apoprotein: cDNA and complete amino acid sequence

摘要: Abstract The apoproteins of pulmonary surfactant (PSAP) are thought to be critical for normal function. They bind phospholipids and enhance their ability form surface films in vitro. These acidic glycoproteins have monomeric molecular weights 36,000, 32,000, 28,000 (PSAP-36, -32, -28). Each member this family proteins has a similar amino acid composition differences electrophoretic mobility due part glycosylation. We derived the full sequence PSAP-32 from nucleotide PSAP cDNA. A cDNA library was prepared canine lung poly(A)+ RNA screened with oligonucleotide probes that were based on NH2-terminal acids determined by Edman degradation. This protein striking feature collagen-like non-collagen-like sequences same polypeptide chain. There 24 Gly-Xaa-Yaa triplets, where Yaa is often hydroxyproline. repeats comprise one-third near NH2 terminus. The remaining two-thirds resistant bacterial collagenase digestion contains possible N-glycosylation site carboxyl probably cysteine involved interchain disulfide bonds.