CALCIUM-DEPENDENT DEGRADATION OF SURFACTANT PROTEIN A BY ACTIVATED NEUTROPHILS DUE TO SERINE PROTEASES

1999 ◽  
Vol 25 (7) ◽  
pp. 595-616 ◽  
Author(s):  
P. Schochett, R. Mora, L. Mark, M.
Keyword(s):  
Serine Proteases ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Calcium Dependent ◽  
Activated Neutrophils

Review: Structural determinants of pattern recognition by lung collectins

2010 ◽  
Vol 16 (3) ◽  
pp. 143-150 ◽  
Author(s):  
Barbara A. Seaton ◽  
Erika C. Crouch ◽  
Francis X. McCormack ◽  
James F. Head ◽  
Kevan L. Hartshorn ◽  
...  
Keyword(s):  
Lipid A ◽  
Protein A ◽  
Structural Similarity ◽  
Acute Phase Reactant ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Surfactant Protein D ◽  
Structural Determinants ◽  
Calcium Dependent ◽  
Anionic Phospholipids

Host defense roles for the lung collectins, surfactant protein A (SP-A) and surfactant protein D (SP-D), were first suspected in the 1980s when molecular characterization revealed their sequence homology to the acute phase reactant of serum, mannose-binding lectin. Surfactant protein A and SP-D have since been shown to play diverse and important roles in innate immunity and pulmonary homeostasis. Their location in surfactant ideally positions them to interact with air-space pathogens. Despite extensive structural similarity, the two proteins show many functional differences and considerable divergence in their interactions with microbial surface components, surfactant lipids, and other ligands. Recent crystallographic studies have provided many new insights relating to these observed differences. Although both proteins can participate in calcium-dependent interactions with sugars and other polyols, they display significant differences in the spatial orientation, charge, and hydrophobicity of their binding surfaces. Surfactant protein D appears particularly adapted to interactions with complex carbohydrates and anionic phospholipids, such as phosphatidylinositol. By contrast, SP-A shows features consistent with its preference for lipid ligands, including lipid A and the major surfactant lipid, dipalmitoylphosphatidylcholine. Current research suggests that structural biology approaches will help to elucidate the molecular basis of pulmonary collectin—ligand recognition and facilitate development of new therapeutics based upon SP-A and SP-D.

scholarly journals Role of P63 (CKAP4) in binding of surfactant protein-A to type II pneumocytes

2008 ◽  
Vol 295 (4) ◽  
pp. L658-L669 ◽  
Author(s):  
Sandra R. Bates ◽  
Altaf S. Kazi ◽  
Jian-Qin Tao ◽  
Kevin J. Yu ◽  
Daniel S. Gonder ◽  
...  
Keyword(s):  
Specific Binding ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Type Ii Cells ◽  
Type Ii ◽  
Calcium Dependent ◽  
Type Ii Pneumocytes ◽  
Surfactant Secretion

We have recently described a putative receptor for lung surfactant protein-A (SP-A) on rat type II pneumocytes. The receptor, P63, is a 63-kDa type II transmembrane protein. Coincubation of type II cells with P63 antibody (Ab) reversed the inhibitory effect of SP-A on secretagogue-stimulated surfactant secretion from type II cells. To further characterize SP-A interactions with P63, we expressed recombinant P63 protein in Escherichia coli and generated antibodies to P63. Immunogold electron microscopy confirmed endoplasmic reticulum and plasma membrane localization of P63 in type II cells with prominent labeling of microvilli. Binding characteristics of iodinated SP-A to type II cells in the presence of P63 Ab were determined. Binding (4°C, 1 h) of 125I-SP-A to type II cells demonstrated both specific (calcium-dependent) and nonspecific (calcium-independent) components. Ab to P63 protein blocked the specific binding of 125I-SP-A to type II cells and did not change the nonspecific SP-A association. A549 cells, a pneumocyte model cell line, expressed substantial levels of P63 and demonstrated specific binding of 125I-SP-A that was inhibited by the P63 Ab. The secretagogue (cAMP)-stimulated increase in calcium-dependent binding of SP-A to type II cells was blocked by the presence of P63 Ab. Transfection of type II cells with small interfering RNA to P63 reduced P63 protein expression, attenuated P63-specific SP-A binding, and reversed the ability of SP-A to prevent surfactant secretion from the cells. Our results further substantiate the role of P63 as an SP-A receptor protein localized on the surface of lung type II cells.

scholarly journals Reversible Calcium-dependent Interaction of Liposomes with Pulmonary Surfactant Protein A

1997 ◽  
Vol 272 (23) ◽  
pp. 14600-14605 ◽  
Author(s):  
Astrid Meyboom ◽  
Dieter Maretzki ◽  
Paul A. Stevens ◽  
Klaus Peter Hofmann
Keyword(s):  
Pulmonary Surfactant ◽  
Protein A ◽  
Surfactant Protein ◽  
Surfactant Protein A ◽  
Calcium Dependent ◽  
Pulmonary Surfactant Protein ◽  
Dependent Interaction

Surfactant protein A binds to IgG and enhances phagocytosis of IgG-opsonized erythrocytes

2006 ◽  
Vol 291 (6) ◽  
pp. L1199-L1206 ◽  
Author(s):  
Peggy M. Lin ◽  
Jo Rae Wright
Keyword(s):  
Immune Complexes ◽  
Protein A ◽  
Surfactant Protein ◽  
Fc Receptor ◽  
Innate Immune ◽  
Surfactant Protein A ◽  
Complement Protein ◽  
Calcium Dependent ◽  
Igg Binding ◽  
Pathogen Clearance

Surfactant protein (SP)-A and SP-D, immunoglobulins, and complement all modulate inflammation within the lung by regulating pathogen clearance. For example, SP-A binds to and opsonizes a variety of bacteria and viruses, thereby enhancing their phagocytosis by innate immune cells such as alveolar macrophages. Immunoglobulins, which bind to antigen and facilitate Fc receptor-mediated phagocytosis, can also activate complement, a family of soluble proteins with multiple host defense functions. Previous studies showed that SP-A and complement protein C1q interact. Since complement protein C1q binds to IgG and IgM immune complexes, the hypothesis tested in this study was that SP-A, which is structurally homologous to C1q, also binds to IgG and affects its functions. SP-A binds to the Fc, rather than the Fab, region of IgG. Binding is calcium dependent but not inhibited by saccharides known to bind to SP-A's carbohydrate recognition domain. The binding of SP-A does not inhibit the formation of immune complexes or the binding of IgG to C1q. In contrast, SP-A enhances the uptake of IgG-coated erythrocytes, suggesting that SP-A might be influencing Fc receptor-mediated uptake. In summary, this study shows a novel interaction between SP-A and IgG and a functional consequence of the binding.

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