Chemical characterization of lung surfactant apoproteins: amino acid composition, <i>N</i>-terminal sequence and enzymic digestion

“…We were able to determine the sequence of the first 33 NH2-terminal amino acids ofPSAP-32 by microsequencing. It has been shown (33) that most probably PSAP-28, -32, and-36 have the same primary sequence with different posttranslational modifications. In addition, the first 4 amino acids of PSAP-28 and the first 14 amino acids ofPSAP-36 have been determined and are identical to PSAP-32.…”

mentioning

confidence: 99%

“…PSAPs are glycoproteins (8,33,35). Two possible Nglycosylation sites are present in the sequence of PSAP, at Asn-3 and Asn-190 (Fig.…”

mentioning

confidence: 99%

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

Benson¹,

Hawgood²,

Schilling³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

151

View full text Add to dashboard Cite

The apoproteins of pulmonary surfactant (PSAP) are thought to be critical for normal surfactant function. They bind to surfactant phospholipids and enhance their ability to form surface ifims in vitro. These acidic glycoproteins have monomeric molecular weights of 36,000, 32,000, and 28,000 . Each member of this family of proteins has a similar amino acid composition and their differences in electrophoretic mobility are due in part to glycosylation. We have derived the full amino acid sequence of PSAP-32 from the nucleotide sequence of PSAP cDNA. A cDNA library was prepared from canine lung poly(A)+ RNA and screened with oligonucleotide probes that were based on the NH2-terminal amino acids of PSAP-32 determined by Edman degradation. This protein has the striking feature of collagen-like and non-collagen-like sequences in the same polypeptide chain. There are 24 Gly-Xaa-Yaa triplets, where Yaa is often hydroxyproline. These repeats comprise one-third of PSAP near the NH2 terminus. The remaining two-thirds of PSAP is resistant to bacterial collagenase digestion and contains a possible N-glycosylation site near the carboxyl terminus. The NH2-terminal one-third of PSAP-32 probably contains the cysteine involved in interchain disulflde bonds.Lung surfactant is a mixture of lipids and proteins in part responsible for the maintenance of alveolar stability by lowering the surface tension at the air-liquid interface (1). To decrease the interfacial tension, lung surfactant must be able to rapidly form a surface film. Previously, King and Clements (2) demonstrated that protein-depleted canine surfactant lipids formed surface films more slowly than the intact surfactant containing about 10% protein. They showed that two proteins (Mr 34,000 and 10,000) in canine lung surfactant were lung-specific (3). While the smaller of these proteins has not been extensively investigated, acidic glycoproteins of Mr 28,000-40,000 have been identified in the lung surfactant from several species (4-11).The ability of isolated canine surfactant proteins of Mr 28,000-40,000 to enhance the rate of surface film formation in vitro has been investigated. These proteins readily associate with synthetic phospholipids (12) and extracted surfactant lipids (13,14) and in the presence of calcium ions promote extremely rapid formation of phospholipid surface films (14). Calcium ions are also required for the rapid spreading of native canine surfactant (13). These results have suggested a critical role for pulmonary surfactaInt apoprotein (PSAP) in normal lung function.Canine PSAP comprises a family of proteins of Mr 28,000, 32,000, and 36,000 (PSAP-28, -32, and -36) (15). They have the same NH2-terminal amino acid, isoleucine, and have nearly identical amino acid compositions. All three contain large quantities of glycine (17 mol %) and proline (10 mol %). Approximately half of the prolines are hydroxylated. These proteins are variably glycosylated. Removal of the carbohydrate from PSAP-32 and PSAP-36 by endoglycosidase F digestion results in p...

show abstract

“…The presence of a large molecular weight protein designated glycoprotein A has been documented in pulmonary surfactant from a number of mammalian species (2,8,11). When bovine surfactant was subjected to SDS-PAGE in the absence of mer- captoethanol, a large proportion of this protein remained at the top of the gel and the remainder appeared as a relatively sharp band at 70,000 daltons (Fig.…”

Section: Discussionmentioning

confidence: 99%

Effect of Reconstituted Pulmonary Surfactant Containing the 6000-Dalton Hydrophobic Protein on Lung Compliance of Prematurely Delivered Rabbit Fetuses

Wallace

Bhavnani

et al. 1988

Pediatr Res

View full text Add to dashboard Cite

Chemical characterization of lung surfactant apoproteins: amino acid composition, N-terminal sequence and enzymic digestion

Cited by 49 publications

References 0 publications

Surfactant lipid peroxidation damages surfactant protein A and inhibits interactions with phospholipid vesicles

Surfactant lipid peroxidation damages surfactant protein A and inhibits interactions with phospholipid vesicles

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

Effect of Reconstituted Pulmonary Surfactant Containing the 6000-Dalton Hydrophobic Protein on Lung Compliance of Prematurely Delivered Rabbit Fetuses

Contact Info

Product

Resources

About