Genomic organization of human surfactant protein D (SP-D). SP-D is encoded on chromosome 10q22.2-23.1

• Published in: The Journal of biological chemistry Vol. 268; no. 4; pp. 2976 - 2983
• Main Authors: CROUCH, E, RUST, K, VEILE, R, DONIS-KELLER, H, GROSSO, L
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 05-02-1993
• Subjects: Amino Acid Sequence; Base Sequence; Biological and medical sciences; chromosome 10; Chromosome Mapping; Chromosomes, Human, Pair 10; Cloning, Molecular; DNA - genetics; Exons; Fundamental and applied biological sciences. Psychology; Genes; Genes. Genome; Glycoproteins - genetics; Humans; In Situ Hybridization; Introns; localization; lungs; man; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; nucleotide sequence; Pulmonary Surfactant-Associated Protein D; Pulmonary Surfactants - genetics; Restriction Mapping; Sequence Alignment; surfactant protein SP-D; Human; Gene; Pulmonary surfactant; In situ; Gene organization; Primary structure; Glycoproteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(18)53869-2

Surfactant protein D (SP-D) is a member of the family of mammalian C-type lectins. SP-D is secreted into the pulmonary airspaces
by lung epithelial cells and is believed to contribute to the lung's defense against inhaled microorganisms. We have previously
characterized cDNAs specific for human SP-D (hSP-D). We now describe the partial characterization of genomic clones for hSP-D
and present evidence for an SP-D gene with coding sequences spanning > 11 kilobases on the long arm of chromosome 10. Genomic
sequencing demonstrated that the signal peptide/amino-terminal domain, the carbohydrate recognition domain, and the linking
sequence between the collagen domain, and carbohydrate recognition domain are each encoded by a single exon, as for surfactant
protein A and the mannose-binding protein C. However, sequencing also demonstrated a unique intron-exon structure for the
collagen domain which is encoded on five exons, including four tandem exons of 117 bp. The latter exons show marked conservation
in the predicted distribution of hydrophilic amino acids, consistent with tandem replication of this collagen gene sequence
during evolution. Segregation analysis of HindIII digests of genomic DNA using specific cDNA probes demonstrated selective
hybridization of radiolabeled hSP-D cDNA to chromosome 10- and 10q-containing human/hamster somatic hybrids. The presence
of SP-D gene sequences was confirmed by DNA amplification using oligomers specific for sequences within the collagen domain
of the hSP-D gene. Fluorescence in situ hybridization of metaphase chromosomes using genomic probes gave selective labeling
of 10q22.2-23.1. We speculate that SP-D is encoded at a locus on 10q that includes the genes for surfactant protein A.