RESUMO
Three of the four known mouse collectin genes have been mapped to chromosome 14. To further characterize the spatial relationship of these genes, a bacterial artificial chromosome (BAC) library of mouse chromosome 14 was screened using mouse surfactant protein (SP)-A and -D complementary DNAs (cDNAs). One large clone hybridized to both SP-A and SP-D cDNAs and was found by polymerase chain reaction (PCR) to contain sequences from one of the mouse mannose-binding lectin genes (Mbl1). We used Southern mapping and subcloning of overlapping restriction fragments to characterize the gene locus. Mapping was confirmed by fluorescent in situ hybridization of fiber-stretched BAC DNA and by Southern hybridization of restriction endonuclease-digested and PCR-amplified genomic DNA. We found that the SP-A, Mbl1, and SP-D genes reside contiguously within a 55-kb region. The SP-A and Mbl1 genes are in the same 5' to 3' orientation and 16 kb apart. The SP-D gene is in the opposite orientation to the two other collectin genes, 13 kb away from the 3' end of the Mbl1 gene. The mouse SP-D gene had not previously been characterized. We found its size (13 kb) and organization to be similar to that of human SP-D. Exon I is untranslated. The second exon is a hybrid exon that contains signal for initiation of translation, signal peptide, N-terminal domain, and the first seven collagen triplets of the collagen-like domain of the protein. Four short exons (III through VI) encode the collagen-like domain of the protein, and exons VII and VIII the linking and the carbohydrate-recognition domains, respectively.
Assuntos
Proteínas de Transporte/genética , Lectina de Ligação a Manose/análogos & derivados , Camundongos/genética , Animais , Sequência de Bases , Southern Blotting , Mapeamento Cromossômico , Cromossomos Bacterianos , Clonagem Molecular , Colectinas , DNA Complementar/análise , Éxons , Biblioteca Genômica , Glicoproteínas/genética , Hibridização in Situ Fluorescente , Íntrons , Lectinas de Ligação a Manose , Modelos Genéticos , Dados de Sequência Molecular , Proteolipídeos/genética , Proteína A Associada a Surfactante Pulmonar , Proteína D Associada a Surfactante Pulmonar , Proteínas Associadas a Surfactantes Pulmonares , Surfactantes Pulmonares/genéticaRESUMO
The human genome contains multiple copies of sequences related to the HERV-K family of endogenous retroviruses, homologous to the B-type mouse mammary tumour virus. A DNA fragment closely resembling an HERV-K long tandem repeat (LTR) was detected in a library of hncDNA clones enriched for sequences from human chromosome 19. Sites showing homology to the sequence of this fragment have been identified on human chromosome 19 by hybridization to previously mapped chromosome 19 cosmids. Thus the distribution of LTR sequences on a specific human chromosome has been mapped for the first time. We estimate the total number of such sites on human chromosome 19 to be at least 110. Many of these sites are located in the vicinity of known genes. The precise localizations (to specific cosmids) of LTR-homologous sequences on chromosome 19 can serve as a reference source and will automatically provide further insight into LTR-gene relationships as new genes are mapped onto the chromosome.
Assuntos
Cromossomos Humanos Par 19 , DNA Viral/análise , Sequências Repetitivas de Ácido Nucleico/genética , Retroviridae/genética , Animais , Sequência de Bases , Mapeamento Cromossômico , Cricetinae , Humanos , Células Híbridas , Dados de Sequência Molecular , Homologia de Sequência do Ácido NucleicoRESUMO
A new technique based on Alu-PCR amplification of hn-RNA is described for the extraction of human-specific transcribed sequences from a hybrid cell line. Arrayed library of hn-cDNA was constructed and characterized by sequencing about 80 individual clones. A high enrichment by human-specific sequences (about 95%) was demonstrated.
Assuntos
Cromossomos Humanos Par 19 , Biblioteca Genômica , Células Híbridas , Transcrição Gênica , Animais , Sequência de Bases , Linhagem Celular , Mapeamento Cromossômico , Cricetinae , Primers do DNA , Humanos , Dados de Sequência Molecular , RNA/genética , Sequências Repetitivas de Ácido NucleicoRESUMO
The sequences of a 1.5 kb long stretch of the 5' flanking region of the gene for the alpha 3 isoform of the catalytic subunit of human Na(+)-K+ ATPase (located on chromosome 19) and of more than a 2 kb stretch of the 5' flanking region of the gene for the alpha 2 isoform (located on chromosome 1) have been determined. Transcription start sites for the gene for the alpha 3 isoform have been mapped at positions -152 and -155 relative to the translation initiation codon by primer extension analysis and S1-nuclease mapping of mRNA from human brain. The 5' flanking region of the gene for isoform alpha 3 contains a CCAAT box on the noncoding chain and six putative Sp1 binding sites. Absence of a conventional TATA box and a high GC content are other features of the region. The 5' upstream region of the gene for the alpha 2 isoform contains potential TATA and CCAAT boxes and one potential Sp1 binding site. Upstream of the putative TATA box there is an octanucleotide repeat, GGGGGAGA, which is also found in several eukaryotic genes in analogous positions. Pairwise comparison of the putative 5' regulatory regions of the genes coding for the different isoforms of the Na(+)-K(+)-ATPase catalytic subunit shows the existence of conserved elements, as well as of oligonucleotide blocks with very different structures. It is suggested that the differences in the primary structure of the 5' upstream regions may provide the basis for tissue-specific expression of the Na(+)-K(+)-ATPase isoforms.
