Biomedical subjects

K Rust

Publications and source records attributed to K Rust.

21 records · Page 2Linked to original sources

PubMed1991

Developmental expression of pulmonary surfactant protein D (SP-D).

Surfactant protein D (SP-D) is a collagenous, surfactant-associated, carbohydrate-binding protein that is synthesized by pulmonary epithelial cells. In the present studies, we examined the expression of SP-D and SP-D mRNA during late fetal (day 17, 19, 21) and early postnatal (day 5) rat lung development using immunochemical, cell-free translation, and Northern hybridization assays. SP-D mRNA and immunoreactive SP-D protein were first detected in guanidine extracts of whole rat lung at 21 days of gestation and reached even higher concentrations during the postnatal period. Likewise, immunoperoxidase studies of rat lung using affinity-purified antibodies to SP-D showed no staining at day 17 or 19, but demonstrated strong cytoplasmic staining of cuboidal epithelial cells lining immature airspaces at day 21 and strong cytoplasmic staining of type II and nonciliated bronchiolar cells in adult lung. SP-D also appeared in amniotic fluid by day 21 and was partially purified by affinity chromatography on maltosyl-agarose under conditions used for the isolation of rat lung SP-D. These studies indicate that the production of SP-D is increased shortly prior to birth, and that the increases in total lung SP-D and SP-D mRNA are temporally correlated with SP-D secretion and the appearance of SP-D in amniotic fluid.

Amino Acid Sequence↗

PubMed1989

Purification and biochemical characterization of CP4 (SP-D), a collagenous surfactant-associated protein.

CP4 is a collagenous glycoprotein (43 kDa, reduced) synthesized by rat type II pulmonary epithelial cells in primary culture (Persson et al., 1988). In order to better characterize this protein, CP4 was isolated from rat bronchoalveolar lavage and EDTA extracts of lung surfactant by adsorption to barium sulfate and elution with sodium citrate followed by reverse-phase HPLC. Amino acid analysis of purified CP4 demonstrated 4-hydroxyproline (Hyp), hydroxylysine (Hyl), and acid-labile components coeluting with Hyl glycosides. In addition, gas-phase amino-terminal microsequencing of two CP4 CNBr peptides demonstrated nonoverlapping collagenous sequences comprised of nine and six Gly-X-Y triplets, containing a total of four residues of Hyp and two of Hyl. There was less than 50% sequence homology of these peptides with the cDNA-derived sequence of the collagenous domain of rat SP-A. Two-dimensional IEF/SDS-PAGE resolved the protein into a charge train of basic isoforms (pI approximately 6-8), similar to those of newly synthesized CP4 and the class D surfactant proteins (Phelps & Taeusch, 1985). Gel filtration of nondenatured CP4 on 4% agarose showed a high apparent molecular mass complex comprised of disulfide-bonded trimers of the 43-kDa subunits. Antibodies to purified lavage CP4 showed specific binding to newly synthesized and surfactant-associated CP4. We propose that CP4 be designated "surfactant protein D" (SP-D) in accordance with an accepted nomenclature for surfactant-associated proteins.

Amino Acid Sequence↗

PubMed1988

CP4: a pneumocyte-derived collagenous surfactant-associated protein. Evidence for heterogeneity of collagenous surfactant proteins.

Type II pneumocytes secrete pulmonary surfactant and are known to synthesize SP-35, a collagenous surfactant-associated protein. Freshly isolated type II cells also synthesize other bacterial collagenase-sensitive and hydroxyproline-containing proteins, including a glycoprotein designated CP4. CP4 was isolated from rat pneumocyte culture medium by immune precipitation with polyclonal antibodies to rat surfactant proteins or by DEAE chromatography and reverse-phase or gel permeation HPLC. CP4 did not cross-react with polyclonal antibodies to SP-35 and was completely resolved from SP-35 by SDS-PAGE (Mr 43K reduced) or isoelectric focusing. Unlike SP-35, which consists of acidic isoforms assembled as disulfide-bonded dimers and multimers, CP4 was secreted as basic isoforms assembled as disulfide-bonded trimers. Differences in primary structure were demonstrated by CNBr and V8 protease peptide mapping. The secretion of both proteins was inhibited by 2,2'-dipyridyl, an inhibitor of posttranslational prolyl and lysyl hydroxylation and collagen triple helix formation. CP4 was isolated from EDTA extracts of rat surfactant. These studies provide evidence for the heterogeneity of pneumocyte-derived collagenous surfactant-associated proteins.

Animals↗