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PubMed1992

Structure and chromosomal localization of the human gene for a brain form of prostaglandin D2 synthase.

We have cloned and characterized the human gene for the 21-kDa brain form of prostaglandin D2 synthase. The gene was isolated from a human genomic lambda library and spans 3600 base pairs. It consists of seven exons and six introns. Southern blot analysis indicates that there is a single copy of the gene in the haploid genome. The transcriptional start site was mapped to a G residue 74 base pairs 5' of the ATG initiation codon. A TATA box-like element (ATAAATA) is situated 21 base pairs upstream of the mRNA start site. The gene was mapped to chromosome 9 bands q34.2-q34.3. The gene bears close resemblance to the genes for murine major urinary protein and ovine beta-lactoglobulin.

Amino Acid Sequence↗
PubMed1992

Structure and chromosomal localization of human arachidonate 12-lipoxygenase gene.

Arachidonate 12-lipoxygenase introduces a molecular oxygen into the C-12 position of arachidonic acid to produce 12(S)-hydroperoxy-5,8,10,14-eicosatetraenoic acid. With the aid of cDNA probes for the enzyme, we isolated overlapping lambda clones encompassing the human 12-lipoxygenase gene and flanking regions from a human genomic library. The gene consists of 14 exons with 13 introns and spans approximately 15 kilobases of DNA. All the exon-intron junctions conform to the GT/AG rule. Neither a typical TATA box nor a CAAT box was found in approximately 1-kb sequence of 5'-upstream region of the translation initiation site. However, this region contains several regulatory elements including four GC boxes, two CACCC boxes, three AP-2 binding sequences, and a glucocorticoid-responsive element. The major transcription initiation site was determined by primer-extension analysis as an adenosine residue at 306 bases upstream from the translation initiation codon. The chromosomal localization of the human 12-lipoxygenase gene was examined by fluorescence in situ hybridization, and the gene was assigned to the sub-band p13.1 of chromosome 17.

Arachidonate 12-Lipoxygenase↗
PubMed2005

Advanced molecular and cytogenetic technologies in birth defect diagnosis and prevention.

Fluorescence in situ hybridization (FISH) has become an important diagnostic tool as an adjunct to classical cytogenetics. FISH utilizes DNA probes comprised of specific nucleic acid sequences tagged with fluorescent molecules to identify the number and location of specific DNA sequences in human cells. These probes can be used to determine various numerical and structural chromosomal aberrations, in many cases, gene dosage and/or structure alterations. Chromosomal abnormalities are responsible for a considerable number of birth defects, and more than 50% of spontaneous abortions. These numbers have been significantly higher since the advent of FISH technology that allows the detection of submicroscopic chromosome alterations. The clinic application of FISH technology in postnatal, prenatal, and preimplantation diagnoses has been playing an important role in the diagnosis and prevention of birth defects. As new technologies evolve, more and more new FISH techniques-such as subtelomeric FISH, multicolor FISH (M-FISH), comparative genomic hybridization (CGH), and microarray-are used in clinical diagnoses, the role of FISH technology in both research and clinical aspects of birth defects will surely continue to expand.

Chromosome Aberrations↗
PubMed1990

Structures and chromosomal localizations of two human genes encoding synaptobrevins 1 and 2.

Synaptobrevins 1 and 2 are small integral membrane proteins specific for synaptic vesicles in neurons. Two cosmid clones containing the human genes encoding synaptobrevins 1 and 2 (gene symbols SYB1 and SYB2, respectively) were isolated and characterized. The coding regions of the synaptobrevin genes are highly homologous to each other and are interrupted at identical positions by introns of different size and sequence. Each gene is organized into five exons whose boundaries correspond to those of the protein domains. Exon I contains part of the initiator methionine codon whereas exon II encodes the variable and immunogenic amino-terminal domain of the synaptobrevins. The third exon comprises the highly conserved central domain of the synaptobrevins, exon IV encodes most of the transmembrane region, and exon V contains the last residues of the transmembrane region and the small intravesicular carboxyl terminus. Comparisons of the synaptobrevin sequences in five species from Drosophila with man indicate a selective conservation of sequences adjacent to the synaptic vesicle surface, suggesting a function at the membrane-cystosol interface. The chromosomal localizations of the human and mouse SYB1 and SYB2 genes were determined using hybrid cell lines. SYB1 was localized to the short arm of human chromosome 12 and to mouse chromosome 6 whereas SYB2 was found on the distal portion of the short arm of human chromosome 17 and on mouse chromosome 11. A PstI restriction fragment length polymorphism was identified at the SYB2 locus.

Amino Acid Sequence↗
PubMed1990

Structure and chromosomal location of the rat ribophorin I gene.

Ribophorin I is a type I transmembrane glycoprotein characteristic of the rough portions of the endoplasmic reticulum where it is thought to play a role in the cotranslational insertion of nascent polypeptides. A rat ribophorin I cDNA was used to isolate four overlapping genomic clones from a rat EMBL3 genomic library. Restriction mapping, Southern blotting, and DNA sequencing showed that these clones, spanning approximately 21 kilobases of chromosomal DNA, include the entire ribophorin I gene, as well as 15 kilobases (kb) of upstream sequences. Southern blotting analysis of DNA from a panel of mouse-Chinese hamster cell hybrids demonstrated that the ribophorin I gene is located on mouse chromosome six. The ribophorin I gene contains 10 exons, seven of which encode the luminal domain of the polypeptide. Exon 8 encodes the trans-membrane domain and small portions of the flanking luminal and cytoplasmic domains. Exons 9 and 10 encode the remainder of the cytoplasmic domain, and the latter includes the 3'-untranslated portion of the mRNA. Six closely spaced transcription start sites located 3 to 24 base pairs upstream from the initiation codon were identified by primer extension analysis and S1 mapping. The sequence of a 1.3-kb region upstream of the cap sites was determined and found to contain three GC-rich potential Sp1-binding sites beginning at -14, -24, and -91 base pairs (bp), two octamer-like sequences at -233 and -1248 bp, and a CAAT-like box at -41 bp. The possible roles of these elements in regulating expression of the ribophorin gene in all cells and in differentiated cell types characterized by a well developed rough endoplasmic reticulum is discussed.

Animals↗
PubMed1985

Relationship between the structure of chromosomal protein HMG1 and its accumulation in the cell nucleus.

When microinjected into the cytoplasm of cultured mammalian cells, non-histone chromosomal protein HMG1 migrates into the nucleus and binds to the chromatin. To define the features of the HMG1 molecule which are essential for this activity, fragments of HMG1 and chemically modified HMG1 molecules were injected into HeLa cells and the capacity of each of these probes to accumulate in the nucleus was measured by an autoradiographic technique. Fragments representing the C-terminal and central portions of HMG1 did not concentrate in the nucleus; a fragment which consisted of the N-terminal two-thirds of the molecule and which lacked the 41 consecutive aspartate and glutamate residues located near the C-terminal end of the molecule accumulated to about the same extent as intact HMG1. When the amino groups of HMG1 were chemically modified, there was a progressive loss in the ability of the protein to accumulate in the nucleus; derivatization of one-fourth of the total amino groups reduced the concentration of microinjected protein in the nucleus relative to that in the cytoplasm to one-half of the original value. In contrast, modification of one-fourth of the total carboxyl groups did not significantly affect the capacity of HMG1 to accumulate in the nucleus, although further modification resulted in decreased nuclear accumulation. Iodination of tyrosine residues was without effect and modification of the cysteine residues had only a modest effect on the ability of HMG1 to concentrate in the nucleus.

Amino Acids↗
PubMedDate not supplied

[Effect of the type of nutrition and aflatoxin B1 on the structure of chromosomes].

Deficiency of the essential nutrients lysine, methionine, threonine and vitamins A, E, C significantly increases the mutagenic environment of somatic cells in growing Wag rats. Aflatoxin B1 produces a pronounced mutagenic effect on the cellular genetic apparatus; this effect is substantially modified due to the nutrition character: it is either intensified or inhibited. The results obtained suggest that the nutritional factors can de used for prevention and elimination of aflatoxin B1-induced mutations.

Aflatoxin B1↗