Isolation and characterisation of a cDNA clone for human apolipoprotein CI and assignment of the gene to chromosome 19

Summary We have synthesised a mixed oligonucleotide 17 bases long and used it to isolate cDNA clones for apolipoprotein CI (apo CI) from an adult liver cDNA library. The partial sequence of one of these clones confirms its identity. We have used this probe and Southern blotting techniques to identify the human apo CI gene in DNA from a series of rodent x human somatic cell hybrids. Our Results provide evidence for the assignment of this gene to human chromosome 19.     

Isolation of cDNA clones coding for rat isovaleryl-CoA dehydrogenase and assignment of the gene to human chromosome 15

Rat liver mRNA encoding the cytoplasmic precursor of mitochondrial isovaleryl-CoA dehydrogenase was highly enriched by polysome immunopurification using a polyclonal monospecific antibody. The purified mRNA was used to prepare a plasmid cDNA library which was screened with two oligonucleotide mixtures encoding two peptides in the amino-terminal portion of mature rat isovaleryl-CoA dehydrogenase. Thirty-one overlapping cDNA clones, spanning a region of 2.1 kbp, were isolated and characterized. The cDNA sequence of a 5'-end clone, rIVD-13 (155 bp), predicts a mitochondrial leader peptide of 30 amino acid residues and the first 18 amino acids of the mature protein. These consecutive 18 residues completely matched the amino-terminal peptide determined by automated Edman degradation of the rat enzyme. The leader peptide contains six arginines, has no acidic residues, and is particularly rich in leucine, alanine, and proline residues. Southern blot analysis of DNAs from human-rodent somatic cell hybrids with an isolated rat cDNA (2 kbp) assigned the isovaleryl-CoA dehydrogenase gene to the long arm of chromosome 15, region q14----qter. The chromosomal assignment was confirmed and further refined to bands q14----q15 by in situ hybridization of the probe to human metaphase cells. This location differs from that of the gene for medium-chain acyl-CoA dehydrogenase, a closely related enzyme, which has been previously assigned to chromosome 1.     

Characterization and chromosome assignment of the porcine AHCY gene for S-adenosylhomocysteine hydrolase

The gene for S-adenosylhomocysteine hydrolase (AHCY) is involved in the regulation of cellular methylation reactions. Here we report the cloning, sequencing, and chromosomal assignment of the porcine AHCY gene. The gene consists of 10 exons spanning approximately 19 kb of genomic DNA. It encodes a protein of 432 amino acids that shows about 96% identity to the orthologous S-adenosylhomocysteine hydrolases from human, rat, and mouse. The porcine AHCY gene is located very close to the agouti signaling protein gene (ASIP) on SSC17q21. The chromosomal localization was subsequently confirmed by RH mapping and the genetic mapping of an intragenic microsatellite that maps to 57 cM on the linkage map of SSC17.     

The human QARS locus: assignment of the human gene for glutaminyl-tRNA synthetase to chromosome 1q32–42

Summary We have used a cDNA encoding the core region of the human glutaminyl-tRNA synthetase to determine the chromosomal localization of the corresponding gene. Southern blots of restricted DNA from a panel of rodent-human cell lines and in situ chromosome hybridization gave identical results showing that the human gene locus for glutaminyl-tRNA synthetase resides on the distal long arm of chromosome 1. There are now nine mapped aminoacyl-tRNA synthetase genes in the human genome.     

Molecular cloning of the c-fms locus and its assignment to human chromosome 5

Molecular clones of the retroviral oncogene v-fms were used to isolate recombinant bacteriophages containing c-fms proto-oncogene sequences from a human placental DNA library. Viral and cellular fms sequences were used in Southern blotting experiments with a panel of 32 human X mouse somatic cell hybrids to assign the human c-fms proto-oncogene to human chromosome 5.     

Isolation of a human laminin B2 (LAMB2) cDNA clone and assignment of the gene to chromosome region 1q25----q31

Laminin B2 is one of the three polypeptide chains of laminin, a large, complex glycoprotein synthesized by a variety of cells and specifically deposited in basement membranes. A cloned cDNA that encodes the human laminin B2 chain was isolated and characterized. The human laminin B2 gene (LAMB2) was assigned to region 1q25----q31 by (1) hybridization of the probe to DNA from a panel of human x mouse somatic cell hybrids containing different human chromosomes and (2) in situ hybridization to isolated metaphase chromosomes.     

Assignment of the gene locus for human phosphoglucomutase 3 to chromosome 6q12-qter

Segregation of human PGM3 has been analyzed in somatic cell hybrids between mouse A9 cells and human fibroblasts carrying a reciprocal translocation: 46,XX, t(6;7) (q12;p14). The enzyme marker segregates with the 7p+ chromosome indicating that the PGM3 gene is located on 6q12 greater than qter.     

The human cytochrome P450 CYP3 locus: assignment to chromosome 7q22-qter

Summary DNA haplotypes (HT) and frameworks (FW) linked to the -globin locus were determined by restriction fragment analysis using eight restriction enzymes on chromosomes bearing the HbA gene (HBB^*A) or the HbE gene (HBB^*E) in the So, an Austro-Asiatic population of northeast Thailand with an HBB^*E frequency near 0.5. All HBB^*E genes were present with FW2, and only two haplotypes were observed (25 HT 27-2,-+-++++-; 10 HT 41-2, +----++-). In a control group from the general population of Northeast Thailand the HT distribution was more diverse, and 2 of 20 HBB^*E genes were present in FW 3. High frequencies of HBB^*E in FW 3 in Southeast Asia are apparently limited to the Khmer population of Cambodia. There were no differences in the hematologic parameters in subjects homozygous for HBB^*E/FW2 or HBB^*E/FW3.     

In situ hybridization to human chromosome 1 of a cDNA probe for the gene encoding the basement membrane heparan sulfate proteoglycan (HSPG)

A mouse partial cDNA clone of the heparan sulfate proteoglycan gene, an important component of basement membranes, has been mapped to human chromosome 1, band p 36.1, by in situ hybridization. No secondary sites of hybridization were observed.     

cDNA and genomic cloning of HRC, a human sarcoplasmic reticulum protein, and localization of the gene to human chromosome 19 and mouse chromosome 7

Histidine-rich calcium binding protein (HRC) is a luminal sarcoplasmic reticulum (SR) protein of 165 kDa identified by virtue of its ability to bind 125I-labeled low-density lipoprotein with high affinity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Hofmann et al., J. Biol. Chem. 264: 8260-8270, 1989). Its role in SR function is unknown. In this report, the gene encoding human HRC was localized to human chromosome 19 and mouse chromosome 7 by hybridization of a human HRC cDNA fragment to a panel of somatic cell hybrids. Known synteny between a portion of human chromosome 19 and a portion of mouse chromosome 7 and in situ hybridization of a biotin-labeled HRC probe to human chromosomes suggest a localization to a region corresponding to 19q13.3. The locus for myotonic dystrophy resides in the region 19q13.2-13.3. Therefore, we considered HRC, a muscle-specific gene, to possibly represent a "candidate gene" for myotonic muscular dystrophy. As a first step toward localizing HRC in relation to the myotonic dystrophy locus, we report the cloning of the human HRC gene, its intron-exon organization, and characterization of several informative polymorphisms to be used in future linkage studies in families with myotonic dystrophy. Of particular interest is an Alu-associated poly-d(GA) sequence located in an intron in the middle of the gene, and two stretches of acidic amino acids in the coding region of exon 1 that vary in length among different individuals.     

Isolation of cDNA clones encoding the beta isozyme of human DNA topoisomerase II and localisation of the gene to chromosome 3p24.

Topoisomerases catalyse the interconversion of topological isomers of DNA and have key roles in nucleic acid metabolism. Human cells express two distinct type II topoisomerase isozymes, designated topoisomerase II alpha (170 kDa form) and topoisomerase II beta (180 kDa form). We have isolated cDNA clones encoding the beta isozyme from a human B-cell library. The proposed coding region for the topoisomerase II beta protein is 4,863 nucleotides long and would encode a polypeptide with a calculated M(r) of 182,705. The predicted topoisomerase II beta protein sequence shows striking similarity (72% identical residues) to that of the human alpha isozyme, and homology to topoisomerase II proteins from Drosophila, yeast and bacteria. Regions of greatest amino acid sequence divergence lie at the extreme N-terminus and over a C-terminal domain comprising approximately 25% of the total protein. We have quantified the level of topoisomerase II beta mRNA in a panel of human tumour cell lines of different origin using an RNase protection assay, and compared the level to that of topoisomerase II alpha mRNA. Topoisomerase II beta mRNA was expressed in haemopoietic, epithelial and fibroblast cell lines, although to different extents, with U937 cells (promonocytic leukaemia) showing a particularly high level. There was no obvious relationship in terms of level of expression between the topoisomerase II alpha and beta genes. We have localised the gene encoding topoisomerase II beta protein to chromosome 3p24 in the human genome.