J D Borchelt

Are you J D Borchelt?

Claim your profile

Publications (2)14.81 Total impact

  • Article: Interaction of surfactant protein A with cellular myosin.
    D Michelis, M Z Kounnas, W S Argraves, E D Sanford, J D Borchelt, J R Wright
    [show abstract] [hide abstract]
    ABSTRACT: The goal of the current investigation was to characterize, purify, and identify the proteins that bind surfactant protein A (SP-A). Several polypeptides were purified by SP-A affinity chromatography, and the 200 kD major polypeptide that reacted with SP-A on ligand blots was purified further by preparative SDS-PAGE. Protein sequencing of proteolytically derived subfragments of this polypeptide gave sequences that corresponded completely with nonmuscle (cellular) myosin heavy chain. The 200 kD polypeptide was then found to be immunoreactive with antibodies against cellular myosin. A smaller polypeptide of 135 kD also binds SP-A and appears to be a proteolytic fragment of the 200 kD peptide. The ability of SP-A to bind myosin was confirmed in a microtiter well assay and was found to be concentration dependent. We speculated that the physiologic relevance of the interaction of SP-A with myosin might be to facilitate clearance of myosin from the alveolar subphase following its release during lung injury. In support of this hypothesis, we found that there were detectable levels of myosin in lavage fluid and that SP-A could indeed enhance uptake and degradation of myosin by alveolar macrophages.
    American Journal of Respiratory Cell and Molecular Biology 01/1995; 11(6):692-700. · 5.13 Impact Factor
  • Source
    Article: Lung surfactant apoprotein SP-A (26-36 kDa) binds with high affinity to isolated alveolar type II cells.
    J R Wright, J D Borchelt, S Hawgood
    [show abstract] [hide abstract]
    ABSTRACT: Pulmonary surfactant is synthesized and secreted by alveolar type II cells. These cells recycle surfactant lipids by an internalization process that is enhanced in vitro by the surfactant proteins with molecular masses of 26-36 kDa (SP-A). SP-A also inhibits the secretion of lipid by type II cells. These results suggest that SP-A may play a role in feedback regulation of surfactant pool size and are consistent with the hypothesis that the type II cell surface has receptors for SP-A. The goal of this study is to characterize the binding of radioiodinated SP-A to isolated rat type II cells. Binding of SP-A to type II cells at 4 degrees C has a K1/2 of approximately 5 X 10(-10) M, is saturable, and is inhibited by excess unlabeled SP-A. Binding is dependent on calcium and is reduced by heat treatment of SP-A. The binding of a proteolytic fragment of SP-A that is produced by collagenase treatment is reduced by excess unlabeled SP-A. The binding of the fragment to macrophages and lung fibroblasts is not inhibited by excess unlabeled SP-A. Trypsinization of the type II cell surface reduces the binding of both intact SP-A and the collagenase-resistant fragment. These results show that SP-A binds to type II cells with high affinity and suggest that these cells have receptors that recognize the carboxyl-terminal domain of SP-A.
    Proceedings of the National Academy of Sciences 08/1989; 86(14):5410-4. · 9.68 Impact Factor
Browse more researchers