Isolation and chromosomal localization of the human glutathione peroxidase gene

We have isolated cDNA clones for the gene, termed GPX1, encoding the major human selenoprotein, glutathione peroxidase. Sequence analysis confirmed previous findings that the unusual amino acid seleno-cysteine is encoded by the opal terminator codon UGA. Southern blot analysis of human genomic DNA with the GPX1 cDNA showed that restriction endonucleases without sites in the probe sequence produced three hybridizing bands at standard stringency, diminishing to one strongly and one weakly hybridizing band at high stringency. In situ hybridization localized the human GPX1 gene to a single site on chromosome 3, at region 3q11-13.1. Thus, three genomic sites bear sequence homology to the GPX1 cDNA, and the one most homologous maps to 3q11-13.1.     

Isolation, mapping, and characterization of two cDNA clones expressed in the cerebellum.

In an effort to characterize genes expressed in the cerebellum, we have isolated two cDNA clones, H11B (D16S286) and 507 (D5S344), that hybridized to a cerebellar cDNA probe. Using a panel of human-rodent somatic cell hybrids, cDNA clone H11B was mapped to human chromosome 16, and clone 507 was mapped to human chromosome 5. TaqI RFLPs were identified with both clones and were used for linkage analysis in the CEPH families. D16S286 was tightly linked to several markers near chromosome 16p13, and D5S344 was tightly linked to several markers on chromosome 5q. Sequence tagged sites or expressed sequence tags were generated from the 3' untranslated regions of both cDNA clones.     

A mouse-human hybrid cell panel for mapping human chromosome 16

A mouse-human hybrid cell panel for human chromosome 16 was constructed from human cell lines with breakpoints on chromosome 16 at p13.11, q13, q22 and q24. Fusions with the human fibroblast line GM3884, t(X;16)(q26;q24) allowed the isolation of clones with either the derivative X or the derivative 16 as the only human chromosome. This was a consequence of both the genes APRT and HPRT being involved in the translocation. The breakpoints of the line GM3884 were confirmed by aphidicolin induction of the common fragile site at 16q23. The results of the fusions with this line suggest a localisation of the APRT gene at 16q24 and confirm the localisation of HPRT to Xq26 to Xq27.3. These hybrid cell lines enable the localisation of genes and DNA fragments to six clearly defined regions. Further localisation within three of these regions is possible by use of the three fragile sites on chromosome 16. In situ hybridisation with the probe pBLUR confirmed that of three lines tested all contained a single human chromosome.     

Localization of the human prealbumin gene to chromosome 18

A human liver cDNA library was screened using an oligonucleotide probe based on the amino acid sequence of human prealbumin. The cDNA insert of one positive clone was sequenced and found to contain the entire coding sequence of human prealbumin plus untranslated 5' and 3' regions. This cDNA was used to probe DNA from a panel of mouse/human somatic cell hybrids. Only those hybrids containing human chromosome 18 showed the human-specific hybridization pattern, thereby localizing the human prealbumin gene to this chromosome.     

Localization of the gene for the erythroid anion exchange protein, band 3 (EMPB3), to human chromosome 17

We have isolated genomic DNA clones which code for the human erythroid membrane protein band 3 (EMPB3). The identification of the gene has been confirmed by comparison of the amino acid sequence derived from the nucleotide sequence for two restriction fragments from the 5' end of the gene. Two exons have been identified. One exon encodes 20 amino acids which are identical to residues 36 to 56 of the band 3 protein, and the other encodes 44 amino acids homologous to residues 118 to 162. Southern analysis of genomic DNA derived from a panel of rodent-human somatic cell hybrids, which retain different complements of human chromosomes, with band 3 probes has allowed us to localize EMPB3 to human chromosome 17. The gene has been further localized between 17q21 and qter by analysis of DNA from somatic cell hybrids which carry derivative chromosomes from translocations involving chromosome 17 and either chromosome 15 or 21.     

Structure, expression and chromosomal localization of human p80-coilin gene.

Coiled bodies (CBs) are non-capsular nuclear bodies with a diameter of 0.3-1 micron and appear to be composed of coiled fibrils. Human autoantibodies to CBs recognize an 80-kD nuclear protein highly enriched in CBs, and this protein has been named p80-coilin. CBs are known to assemble and disassemble during the cell cycle, with the highest number of CBs occurring at mid to late G1 where p80-coilin is assembled into several small nuclear body-like structures. In S and G2 phases, CBs become larger and their number decreases and often they are undetectable during mitosis. Using a human autoantibody as a probe for expression cloning, we initially isolated a partial cDNA encoding p80-coilin. In this report, the 5' end of the complete cDNA for p80-coilin was obtained using the 5'-RACE (rapid amplification of cDNA ends) methodology. The size of the reconstructed full-length cDNA corresponds to the 2.7-kb mRNA detected in Northern blot analysis. The complete p80-coilin protein consists of 576 amino acids with a predicted molecular mass of 62,608. A putative p80-coilin pseudogene was also detected during the rescreening of p80-coilin cDNA. To confirm the validity of the cDNA sequence, three overlapping genomic DNA clones representing the human p80-coilin gene were selected for further analysis. The complete gene for p80-coilin contains 7 exons spanning approximately 25kb. Sequence analysis of exons 1 and 2 in genomic DNA clones confirmed the accuracy of the 5' cDNA sequence derived from the 5'-RACE procedure. Furthermore, the human p80-coilin gene was localized to chromosome 17q22-23 by fluorescence in situ hybridization.     

Exon-intron organization and chromosomal localization of the mouse monoglyceride lipase gene

Monoglyceride lipase (MGL) functions together with hormone-sensitive lipase to hydrolyze intracellular triglyceride stores of adipocytes and other cells to fatty acids and glycerol. In addition, MGL presumably complements lipoprotein lipase in completing the hydrolysis of monoglycerides resulting from degradation of lipoprotein triglycerides. Cosmid clones containing the mouse MGL gene were isolated from a genomic library using the coding region of the mouse MGL cDNA as probe. Characterization of the clones obtained revealed that the mouse gene contains the coding sequence for MGL on seven exons, including a large terminal exon of approximately 2.6 kb containing the stop codon and the complete 3' untranslated region. Two different 5' leader sequences, diverging 21 bp upstream of the predicted translation initiation codon, were isolated from a mouse adipocyte cDNA library. Western blot analysis of different mouse tissues revealed protein size heterogeneities. The amino acid sequence derived from human MGL cDNA clones showed 84% identity with mouse MGL. The mouse MGL gene was mapped to chromosome 6 in a region with known homology to human chromosome 3q21.     

Isolation of a cDNA clone for the human laminin-B1 chain and its gene localization.

A cDNA clone encoding the B1 chain of human laminin has been isolated from a human endothelial cell cDNA library. With use of this probe and a panel of rodent/human somatic-cell hybrids and in situ hybridization, the gene for the human laminin-B1 chain has been localized to chromosome 7, band q31.     

Cloning of a complementary DNA encoding a new mouse B lymphocyte differentiation antigen, homologous to the human B1 (CD20) antigen, and localization of the gene to chromosome 19

The human B1 (CD20) molecule is a differentiation Ag found only on the surface of B lymphocytes. This structurally unique phosphoprotein plays a role in the regulation of human B cell proliferation and differentiation. In order to determine whether this structure is also expressed by murine B cells, cDNA clones that encode the mouse equivalent of the B1 molecule were isolated. The longest murine cDNA clone isolated, pmB1-1, contained a 1.4-kb insert with an 873 base pair open reading frame that encodes a protein of 32 kDa. The predicted mouse B1 protein contains three hydrophobic domains that may span the membrane four times and shares a 73% amino acid sequence homology with the human B1 protein. The pmB1-1 cDNA probe was used to examine mB1 mRNA expression. Northern blot analysis indicated that pmB1-1 hybridized with two mRNA species of 2.3 and 3.0 kb that were expressed only in murine spleen lymphocytes, in B lineage cell lines representing mature B cells, and were weakly expressed in one of two plasmacytoma cell lines. pmB1-1 failed to hybridize with RNA isolated from murine T cell lines, thymus, and nonlymphoid tissues. Southern blot analysis indicated that mB1 was encoded by a single copy gene. In situ hybridization localized the mB1 gene to chromosome 19 band B, a region that also contains the genes that encode the Ly-1, Ly-10, and Ly-12 Ag. These results suggest that only B cells express this heretofore undescribed murine cell-surface protein that is structurally homologous with the membrane-embedded human B1 Ag.     

Sequence,gene structure,and expression pattern of CTNNBL1, a minor-class intron-containing gene--evidence for a role in apoptosis

We have identified and characterized a cDNA designated CTNNBL1 (catenin (cadherin-associated protein), beta-like 1) coding for a protein of 563 amino acids having predicted structural homology to beta-catenin and other armadillo (arm) family proteins. CTNNBL1 is expressed in multiple human tissues, and its sequence is conserved across widely divergent species. The human CTNNBL1 gene on chromosome 20q11.2 contains 16 exons spanning > 178 kb. Intron 4 is a minor-class intron bearing AT at the 5' splice site and AC at the 3' splice site. An acidic domain, as well as a putative bipartite nuclear localization signal, a nuclear export signal, a leucine-isoleucine zipper, and phosphorylation motifs are present in the protein sequence. Transient expression of CTNNBL1 in CHO cells results in localization to the nucleus and apoptosis. The rate of cell death was higher when cells were transfected with a carboxy-terminal fragment of CTNNBL1, suggesting that the apoptosis-inducing activity is a function of this region.     

Localization of the beta A4-crystallin gene (CRYBA4) on human chromosome 22 in the region q11.2-->q13.1.

The chromosomal localization of the human gene (CRYBA4) coding for the eye lens protein beta A4-crystallin has been carried out using a nearly full-length cDNA clone encoding bovine beta A4-crystallin. A panel of 21 human-mouse or human-hamster hybrid cell lines derived from different parental combinations was characterized with respect to the human chromosomal content and the presence of well established human chromosome-specific markers. These panels were screened for the presence of CRYBA4 using the bovine cDNA clone as a probe. A 100 percent concordance was observed between the presence or absence of the CRYBA4 and human chromosome 22 indicating that the gene resides on this chromosome. By using cell hybrids containing translocated chromosome 22 segments, the localization could be refined to the region 22q11.2-->q13.1.