title: Mouse surfactant protein-D. cDNA cloning, characterization, and gene localization to chromosome 14.
abstract: Surfactant protein-D (SP-D) is a collectin found associated with surfactant in the lung. SP-D has also been functionally characterized as an opsonin for diverse microorganisms and a chemoattractant for phagocytic cells. To determine the structure of mouse SP-D, we isolated and characterized clones from a B6/CBAF1J strain lung cDNA library using a PCR-derived genomic probe. The deduced sequence predicts a 19-amino acid signal sequence, a 25-amino acid long NH2 terminus with two cysteines, followed by an uninterrupted collagen domain with 59 Gly-X-Y repeats. Next, a short "neck" domain of 28 amino acids, with a potential to form trimeric alpha-helical coiled coil is found ending in a COOH-terminal 125-amino acid carbohydrate recognition domain. The mature mouse SP-D protein of 355 amino acids shows strong homology to rat (92% identity), human (76%), and bovine (72%) SP-D amino acid sequences. Northern blot and RT-PCR analysis revealed that the mouse SP-D gene is expressed predominantly in lung and, surprisingly, also in heart, stomach, and kidney but not in brain. In contrast, mouse surfactant protein-A (SP-A) mRNA expression was found to be restricted to lung. Human lung and stomach, but not heart or liver, were found to express SP-D mRNA, as determined by PCR. The mouse SP-D gene (Sftp4) has been localized to chromosome 14 (to a region syntenic to human chromosome 10), closely linked to the genes for other collagenous lectins, mannose-binding protein-A (MbI1), and SP-A (Sftp1).
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D006023:Glycoproteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D016133:Polymerase Chain Reaction; D011510:Proteolipids / Q000235:genetics; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D006023:Glycoproteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger