Disease relevance of SFTPD

• The lectin precipitation and lectin blot assays showed that the truncated SP-D could bind to influenza A virus as well as native SP-D did [1].
• The recombinant SP-D caused dose-dependent and calcium-dependent agglutination of E. coli Y1088 [1].
• Knock-out mice deficient in SP-D have a disturbed homeostasis of pulmonary surfactant and suffer from oxidative stress leading to pulmonary inflammation upon microbial challenge [2].

High impact information on SFTPD

• The CDM bound mannose-Sepharose and phosphatidylinositol (PI) as well as SP-D, but the binding to mannosyl bovine serum albumin and glucosylceramide was diminished by approximately 60% [3].
• Surfactant protein D (SP-D) is a member of the C-type lectin superfamily with four distinct structural domains: an amino terminus involved in forming intermolecular disulfides, a collagen-like domain, a neck region, and a carbohydrate recognition domain [3].
• The N-terminal sequence (27 amino acids) showed 56% identity with bovine SP-D and 44% identity to bovine conglutinin [4].
• Surfactant protein D (SP-D) is a carbohydrate-binding glycoprotein containing a collagen-like domain that is synthesized by alveolar type II epithelial cells [5].
• There are 6 cysteine residues present in rat SP-D: 2 in the NH2-terminal noncollagenous segment and 4 in the COOH-terminal carbohydrate-binding domain [5].

Biological context of SFTPD

• The derived amino acid sequence for bovine SP-D shows a higher (78%) level of identity to the sequence of conglutinin than to the sequence of human or rat SP-D (67 and 65% respectively) [6].
• With the perspective of being able to identify surfactant protein D (SP-D) polymorphisms associated with immune-compromised phenotypes in cattle, we have characterized the gene encoding bovine SP-D and its proximal promoter [7].
• In addition, SP-D inhibits the generation of radical oxygen species or the propagation of lipid peroxidation [2].
• Using a set of IAV strains that differed in the level and site of glycosylation, and a panel of recombinant collectins, we found that binding of SP-D to the globular domain of the HA was critical in mediating the inhibition of viral haemagglutination activity and infectivity [8].
• Specific binding to FA chains was also demonstrated by solution phase competition for FA binding to acrylodan-labeled FA binding protein (ADIFAB), and by overlay of thin layer chromatograms with SP-D [9].

Anatomical context of SFTPD

• RT-PCR analysis revealed that bovine SP-D is heavily expressed in the lung and the trachea, but also in segments of the gastrointestinal tract, the mammary glands and the salivary glands [7].
• Surfactant protein D (SP-D) is a lung-specific protein that is synthesized and secreted by lung epithelial cells and is believed to play an important role in lung host defence [1].

Associations of SFTPD with chemical compounds

• The most efficient inhibitors of SP-D binding were alpha-glucosyl-containing saccharides (e.g. isomaltose, maltose, malotriose) [10].
• SP-D showed quantitative binding to maltosyl-agarose and was specifically eluted with maltose or EDTA [10].

Other interactions of SFTPD

• Since SP-D appears to be a lung-specific protein, it seems probable that the liver is the primary site of synthesis of conglutinin [6].
• Of interest, the expression of the BC mRNA, as determined by RNase protection assay, is restricted to liver, unlike bovine SP-D, a lung-surfactant protein [11].
• CL-43, lung surfactant protein D (SP-D) and conglutinin showed no complement-activating properties under the same conditions [12].

Analytical, diagnostic and therapeutic context of SFTPD

• The use of a polymerase chain reaction (PCR)-derived DNA probe for bovine SP-D in Northern blotting studies yielded a signal from bovine liver mRNA as well as the expected signal from bovine lung mRNA [6].
• On gel-filtration, a proportion of the SP-D preparation behaved, as expected, as a molecule with an apparent molecular mass of 600 kDa [13].
• A collagen domain deletion mutant (CDM) of SP-D was created by site-directed mutagenesis [3].
• Saccharide-substituted bovine serum albumins (BSA neoglycoproteins) were adsorbed to plastic wells, and binding of purified SP-D was quantified with monospecific antibodies to SP-D using an indirect immunoassay [10].

References