Partial Gene Structure and Assignment to Chromosome 2q37 of the Human Inwardly Rectifying KChannel (Kir7.1) Gene (KCNJ13)

The novel weakly inward rectifying potassium channel K_ir7.1 is a low-conductance channel that is predominantly expressed in epithelial cells. Here we describe a partial genomic characterization and the chromosomal assignment of the human K_ir7.1 gene (KCNJ13). Analysis of the genomic structure using a PCR-based approach revealed a single 2088-bp intron in the coding region ofKCNJ13. PCR analysis of monochromosomal and radiation hybrid panels assignsKCNJ13to band 2q37 between markers D2S331 and D2S345. In addition, a single nucleotide polymorphism (C524→T), leading to an exchange of a Thr with an Ile residue at amino acid position 175, was found.     

Assignment of the gene coding for human catalase to the short arm of chromosome 11

Human and murine catalases can be separated electrophoretically as single bands of different mobility. In man-mouse somatic cell hybrids, however, detection of human catalase is precluded by the complexity of banding patterns resulting from interference of a catalase-modifying enzyme activity. We have identified human catalase in hybrid clones by Laurel electrophoresis employing a specific anti-human catalase antibody, and by exploiting heat stability differences. Catalase co-segregates with LDH A and is probably located on the short arm of chromosome 11.     

Regional mapping of human chromosome 3. Assignment of a glutathione peroxidase-1 gene to 3p13→3q12

Summary The segregation of human glutathione peroxidase-1 (GPX1, EC 1.11.1.9) was followed in a series of human-mouse somatic cell hybrids carrying various fragments of human chromosome 3. These fragments originated from translocations in the parental human fibroblasts or from spontaneous deletions which occurred during the cultivation of hybrid clones. The smallest region of overlap found for the position of GPX 1 was 3p133q12.     

The potassium channel gene HK1 maps to human chromosome 11p14.1, close to the FSHB gene

Transiently activating (A-type) potassium (K) channels are important regulators of action potential and action potential firing frequencies. HK1 designates the first human cDNA that is highly homologous to the rat RCK4 cDNA that codes for an A-type K-channel. The HK1 channel is expressed in heart. By somatic cell hybrid analysis, the HK1 gene has been assigned to human chromosome 11p13-p14, the WAGR deletion region (Wilms tumor, aniridia, genito-urinary abnormalities and mental retardation). Subsequent pulsed field gel (PFG) analysis and comparison with the well-established PFG map of this region localized the gene to 11p14, 200–600kb telomeric to the FSHB gene.     

Possible assignment of the glyoxalase I (GLO) gene to chromosome 6 using man-mouse somatic cell hybrids

Summary A correlation between the expression or absence of human glyoxalase I and chromosome 6 (as well its markers ME₁, IPO-B, and PGM₃) was observed in man-mouse somatic cell hybrids. This segregation pattern indicates that the GLO gene is situated on chromosome 6.

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Zusammenfassung In Hybriden somatischer Zellen zwischen Maus und Mensch wurde eine Korrelation zwischen Vorhandensein bzw. Abwesenheit der menschlichen Glyoxalase I und von Chromosom 6 (sowie seinen Markern ME₁, IPO-B und PGM₃) ermittelt. Diese Korrelation spricht dafür, daß das GLO-Gen auf Chromosome 6 liegt.

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Supported by the Deutsche Forschungsgemeinschaft BE 352/8 and GR 373/6.     

Mapping of DNA markers linked to the cystic fibrosis locus on the long arm of chromosome 7.

We have used a panel of eight human/mouse somatic-cell hybrids, each containing various portions of human chromosome 7, and three patient cell lines with interstitial deletions on chromosome 7 for localization of six DNA markers linked to the cystic fibrosis locus. Our data suggest that D7S15 is located in the region 7 cen----q22, that MET is located in 7q22----31, and that D7S8 and 7C22 are located in q22----q32. The hybridization results for COL1A2 and TCRB are consistent with their previous assignment to 7q21----q22 and 7q32, respectively. Given the location of these six markers and their linkage relationships, it is probable that the cystic fibrosis locus is in either the distal region of band q22 or the proximal region of q31. Using the same set of cell lines, we have also examined the location of another chromosome 7 marker PGY1. The data show that PGY1 is located in the region 7cen----q22, a position very different from its previous assignment.     

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.     

Characterization of a set of X-linked sequences and of a panel of somatic cell hybrids useful for the regional mapping of the human X chromosome

Summary We have characterized 19 DNA fragments originating from the human X chromosome. Most of them have been isolated from an X chromosome genomic library (Davies et al. 1981) using a systematic screening procedure. These DNA probes have been used to search for restriction fragment length polymorphisms (RFLP). The frequency of restriction polymorphisms (1 per 350 bp analysed) was lower than expected from data obtained with autosomal fragments. The various probes have been mapped within 12 subchromosomal regions using a panel of human-rodent hybrid cell lines. The validity of the panel was established by hybridization experiments performed with 27 X-specific DNA probes, which yielded information on the relative position of translocation break-points on the X chromosome. The DNAs from the various hybrid lines are blotted onto a reusable support which allows one to quickly map any new X-specific DNA fragment. The probes already isolated should be of use to map unbalanced X chromosome aberrations or to characterize new somatic cell hybrid lines. The probes which detect RFLPs define new genetic markers which will help to construct a detailed linkage map of the human X chromosome, and might also serve for the diagnosis of carriers or prenatal diagnosis.     

Regional assignment of 41 human DNA fragments on chromosome 7 by means of a somatic cell hybrid panel

Summary To detect new restriction fragment length polymorphisms that would cover human chromosome 7 with a network of genetic landmarks, a chromosome 7-specific phage gene library was screened for human single-copy fragments. With use of a somatic cell hybrid panel containing defined regions of human chromosome 7, 41 cloned human single-copy sequences were assigned to five regions of this chromosome. Of special importance are the cell hybrid clones GM1059Rag5 and 7851Rag10-1, derived from human cells with interstitial deletions spanning the bands 7q22-q32, within which the cystic fibrosis gene is located. Twelve new probes are described in 7q22-q32, five of which detect a total of six RFLPs.