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At least 307 records · Page 17Linked to original sources
PubMed2006

Exploration and grading of possible genes from 183 bacterial strains by a common protocol to identification of new genes: Gene Trek in Prokaryote Space (GTPS).

A large number of complete microorganism genomes has been sequenced and submitted to the public database and then incorporated into our complete genome database, Genome Information Broker (GIB, http://gib.genes.nig.ac.jp/). However, when comparative genomics is carried out, researchers must be aware that there are protein-coding genes not confirmed by homology or motif search and that reliable protein-coding genes are missing. Therefore, we developed a protocol (Gene Trek in Prokaryote Space, GTPS) for finding possible protein-coding genes in bacterial genomes. GTPS assigns a degree of reliability to predicted protein-coding genes. We first systematically applied the protocol to the complete genomes of all 123 bacterial species and strains that were publicly available as of July 2003, and then to those of 183 species and strains available as of September 2004. We found a number of incorrect genes and several new ones in the genome data in question. We also found a way to estimate the total number of orthologous genes in the bacterial world.

Bacteria↗
PubMed1982

A rat tRNA gene cluster containing the genes for tRNAPro and tRNALys. Analysis of nucleotide sequences of the genes and the surrounding regions.

A lambda clone carrying a rat DNA fragment of 11.9 kb was isolated from a rat gene library with total rat tRNA as a probe. Nucleotide sequence analysis revealed that the DNA fragment contained six tRNA genes, three for tRNAPro and three for tRNALys. Of the six genes all but one tRNAPro gene have the same polarity. Each tRNA gene is separated by a DNA region of 0.1 to 3.6 kb. The 5'-flanking regions of the six rat genes in the cluster do not have any significant sequence homology, but in the 3'-flanking region, each gene has a short T cluster, which is supposed to be a transcription termination signal.

Animals↗
PubMed1987

The nucleotide sequence of a 3.2 kb segment of mitochondrial maxicircle DNA from Crithidia fasciculata containing the gene for cytochrome oxidase subunit III, the N-terminal part of the apocytochrome b gene and a possible frameshift gene; further evidence for the use of unusual initiator triplets in trypanosome mitochondria.

A 3.2 kb segment of the maxicircle of Crithidia fasciculata mitochondrial (mt) DNA contains the gene for cytochrome oxidase subunit III (coxIII), the N-terminal portion of the gene for apocytochrome b (cytb) and two partially overlapping Unassigned Reading Frames (C.URF2/1). Transcript analysis of the segment reveals that both the coxIII gene and the C.URF2/1 area are transcribed into a pair of RNA products. With the C. fasciculata gene version as a probe, a coxIII gene could not be detected in nuclear and mtDNA of Trypanosoma brucei, indicating that the cytochrome oxidases of these two closely related trypanosome species may differ. The nucleotide homology in the N-terminal region of the coxIII and cytb genes in T. brucei, Leishmania tarentolae and C. fasciculata starts at a UUA leucine codon, which adds further support to the hypothesis that apart from AUG, other initiator triplets are used in trypanosomal mitochondria: UUG, CUG and UUA, all triplets coding for leucine in the universal code. Finally, the possibility is discussed that the two overlapping URFs (C.URF2/1) in fact represent a single, frameshift containing, gene.

Amino Acid Sequence↗
PubMed2005

Gene trap and gene inversion methods for conditional gene inactivation in the mouse.

Conditional inactivation of individual genes in mice using site-specific recombinases is an extremely powerful method for determining the complex roles of mammalian genes in developmental and tissue-specific contexts, a major goal of post-genomic research. However, the process of generating mice with recombinase recognition sequences placed at specific locations within a gene, while maintaining a functional allele, is time consuming, expensive and technically challenging. We describe a system that combines gene trap and site-specific DNA inversion to generate mouse embryonic stem (ES) cell clones for the rapid production of conditional knockout mice, and the use of this system in an initial gene trap screen. Gene trapping should allow the selection of thousands of ES cell clones with defined insertions that can be used to generate conditional knockout mice, thereby providing extensive parallelism that eliminates the time-consuming steps of targeting vector construction and homologous recombination for each gene.

Animals↗
PubMed1990

Construction of hybrid xylE genes between the two duplicate homologous genes from TOL plasmid pWW53: comparison of the kinetic properties of the gene products.

The two xylE genes for catechol 2,3-oxygenase, encoded by TOL plasmid pWW53, carry a common SalI restriction site within the reading frame. Each gene was cut at the SalI site and the 5' end of each gene spliced to the 3' end of the other to form hybrid genes, from both of which catalytically active catechol 2,3-oxygenase activities were expressed. The kinetic parameters were determined for the gene products of both the hybrid and the wild-type xylE genes with catechol, 3-methylcatechol and 4-methylcatechol as substrates. Comparison of the results suggested firstly, that the C-terminal regions of the enzymes determined both the binding and the catalytic specificity, and, secondly, that the N-terminal region of one of the enzymic gene products contained a secondary binding site which caused inhibition by excess substrate for methylcatechol substrates but not for catechol. One of the wild-type enzymes appeared to have an intrinsically higher activity for all three substrates than the other. This higher activity depended on the presence of both its C- and N-terminal regions, and in both hybrid enzymes, which contained only one of these regions, activity was significantly reduced.

Binding Sites↗
PubMed1998

Rhodobacter capsulatus genes encoding form I ribulose-1,5-bisphosphate carboxylase/oxygenase (cbbLS) and neighbouring genes were acquired by a horizontal gene transfer.

Analysis of the nucleotide sequence of the form I ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes (cbbL and cbbS) of the non-sulfur purple bacterium Rhodobacter capsulatus indicated that the deduced amino acid sequence of the large subunit was not closely homologous to the large subunit from related organisms. Indeed, phylogenetic analysis suggested that the large subunit protein (CbbL) more closely resembled the enzyme from alpha/beta/gamma purple bacteria and cyanobacteria and is within a 'green-like' radiation of the RubisCO phylogenetic tree, well separated from CbbL of the related organism Rhodobacter sphaeroides. A cbbQ gene was discovered downstream of cbbS in Rh. capsulatus, a gene arrangement which also appears to be limited to certain organisms containing a 'green-like' RubisCO. Upstream, and divergently transcribed from cbbLSQ, is a gene (cbbRI) that encodes a LysR-type transcriptional activator. Phylogenetic analysis of the deduced amino acid sequence of CbbRI also suggests that this protein is quite distinct from the Rh. sphaeroides CbbR protein, and is even distinct from the previously described CbbRII protein, the gene of which is upstream and divergently transcribed from the cbbII operon of Rh. capsulatus. Interestingly, Rh. capsulatus CbbRI is more closely related to CbbR from bacteria whose RubisCO falls within the 'green-like' radiation of the CbbL tree. These studies suggest that the cbbRI-cbbL-cbbS-cbbQ genes were acquired by Rh. capsulatus via horizontal gene transfer from a bacterial species containing a 'green-like' RubisCO.

Amino Acid Sequence↗
PubMed1994

Mutational analysis of the Bordetella pertussis fim/fha gene cluster: identification of a gene with sequence similarities to haemolysin accessory genes involved in export of FHA.

The chromosome of Bordetella pertussis harbours a region of 27 contiguous kb, which contains the bvg, fha and fim genes, involved in the co-ordinate regulation of virulence genes, FHA production and fimbriae production, respectively. The linkage of FHA and fimbrial genes has resulted in some confusion concerning the existence and location of genes required for the production of FHA and the function of the fimbrial genes fimB-D, which were proposed to be involved in both FHA and fimbriae biosynthesis. Through the use of non-polar mutations in each of these genes, we found that fimB-D are required for the production of both serotype 2 and 3 fimbriae, but not for FHA biosynthesis. Furthermore, a large open reading frame, designated fhaC, was identified downstream of fimD. It was shown that fhaC is essential for FHA production but not for fimbriae biogenesis. We propose that insertion mutations in fimB-D affect FHA production because of polar effects on fhaC expression. An insertion in the region downstream of fhaC had only a slight effect on FHA and fimbriae production. The fhaC gene product shows homology with ShIB and HpmB, two outer membrane proteins involved in export and activation of the haemolysins, ShIA and HpmA, of Serratia marcescens and Proteus mirabilis, respectively. Homology is also observed between the N-termini of FHA, ShIA and HpmA. Export of the haemolysins requires the N-termini of these molecules, and when this region was removed from FHA by an in-frame deletion, FHA biosynthesis was abolished. These results suggest that the N-terminus of FHA interacts with FhaC, and that as a result FHA is transported across the outer membrane.

Adhesins, Bacterial↗
PubMed1990

The nucleotide sequence of the Desulfovibrio gigas desulforedoxin gene indicates that the Desulfovibrio vulgaris rbo gene originated from a gene fusion event.

Expression of the rbo gene from Desulfovibrio vulgaris Hildenborough in Escherichia coli minicells and Western blotting (immunoblotting) of Desulfovibrio cell extracts with antibodies raised against a synthetic peptide indicated the presence of a 14-kDa polypeptide product, as expected from the gene sequence. Cloning and sequencing of the gene (dsr) for desulforedoxin, a 4-kDa redox protein from Desulfovibrio gigas, showed that it is formed by expression of an autonomous gene of 111 bp, not by processing of a 14-kDa protein. The results indicate that the rbo gene product, which has a 4-kDa desulforedoxin domain as the NH2 terminus, may have arisen by gene fusion. Shuffling and fusion of genes for redox protein domains can explain the large variety of redox proteins found in sulfate-reducing bacteria.

Amino Acid Sequence↗
PubMed2000

Zac1 (Lot1), a potential tumor suppressor gene, and the gene for epsilon-sarcoglycan are maternally imprinted genes: identification by a subtractive screen of novel uniparental fibroblast lines.

Imprinted genes are expressed from one allele according to their parent of origin, and many are essential to mammalian embryogenesis. Here we show that the epsilon-sarcoglycan gene (Sgce) and Zac1 (Lot1) are both paternally expressed imprinted genes. They were identified in a subtractive screen for imprinted genes using a cDNA library made from novel parthenogenetic and wild-type fibroblast lines. Sgce is a component of the dystrophin-sarcoglycan complex, Zac1 is a nuclear protein inducing growth arrest and/or apoptosis, and Zac1 is a potential tumor suppressor gene. Sgce and Zac1 are expressed predominantly from their paternal alleles in all adult mouse tissues, except that Zac1 is biallelic in the liver and Sgce is weakly expressed from the maternal allele in the brain. Sgce and Zac1 are broadly expressed in embryos, with Zac1 being highly expressed in the liver primordium, the umbilical region, and the neural tube. Sgce, however, is strongly expressed in the allantoic region on day 9.5 but becomes more widely expressed throughout the embryo by day 11.5. Sgce is located at the proximal end of mouse chromosome 6 and is a candidate gene for embryonic lethality associated with uniparental maternal inheritance of this region. Zac1 maps to the proximal region of chromosome 10, identifying a new imprinted locus in the mouse, homologous with human chromosome 6q24-q25. In humans, unipaternal disomy for this region is associated with fetal growth retardation and transient neonatal diabetes mellitus. In addition, loss of expression of ZAC has been described for a number of breast and ovarian carcinomas, suggesting that ZAC is a potential tumor suppressor gene.

Animals↗
PubMed1983

Cloning of Saccharomyces cerevisiae DNA replication genes: isolation of the CDC8 gene and two genes that compensate for the cdc8-1 mutation.

The CDC8 gene, whose product is required for DNA replication in Saccharomyces cerevisiae, has been isolated on recombinant plasmids. The yeast vector YCp50 bearing the yeast ARS1, CEN4, and URA3 sequences, to provide for replication, stability, and selection, respectively, was used to prepare a recombinant plasmid pool containing the entire yeast genome. Plasmids capable of complementing the temperature-sensitive cdc8-1 mutation were isolated by transformation of a cdc8-1 mutant and selection for clones able to grow at the nonpermissive temperature. The entire complementing activity is carried on a 0.75-kilobase fragment, as revealed by deletion mapping. This fragment lies 1 kilobase downstream from the well-characterized sup4 gene, a gene known to be genetically linked to CDC8, thus confirming that the cloned gene corresponds to the chromosomal CDC8 gene. Two additional recombinant plasmids that complement the cdc8-1 mutation but that do not contain the 0.75-kilobase fragment or any flanking DNA were also identified in this study. These plasmids may contain genes that compensate for the lack of CDC8 gene product.

Cloning, Molecular↗
PubMed2001

Screening for mutations in the steroidogenic acute regulatory protein and steroidogenic factor-1 genes, and in CYP11A and dosage-sensitive sex reversal-adrenal hypoplasia gene on the X chromosome, gene-1 (DAX-1), in hyperandrogenic hirsute women.

Abstract Abnormalities in adrenal and/or ovarian steroidogenesis are found in most patients with hirsutism. The rate-limiting step in the synthesis of steroids in the ovary and the adrenal is the conversion of cholesterol into pregnenolone by cholesterol side-chain cleavage enzyme (P450scc), encoded by the gene CYP11A, after cholesterol is introduced into the mitochondria by the steroidogenic acute regulatory protein (StAR). DAX-1 is a repressor of StAR gene expression, and steroidogenic factor-1 (SF-1) is a regulator of CYP11A, DAX-1, and StAR gene. Mutations in any of these factors resulting in gain of function, or loss of repression, of StAR or P450scc might contribute to the steroidogenic abnormalities present in hirsute patients. In the present study we have screened, using heteroduplex analysis, the genes encoding StAR and SF-1 as well as DAX-1 and CYP11A for mutations in genomic DNA from 19 women presenting with hirsutism and increased serum androgen levels. When variants were found, analysis was extended to a larger group of hyperandrogenic patients and nonaffected women. Two variants were identified in the SF-1 gene. A G-->C change in exon 6, resulting in an Arg(365)Pro mutation, was found in 1 of 45 patients, but not in controls. Also, a Gly(146)Ala missense mutation, resulting from a G-->C change in exon 4, was found in 2 of 48 patients and in 2 of 50 nonaffected individuals. We identified a C-->T base pair change at position -33 of the StAR gene. Three of 48 patients and 3 of 43 controls presented this variant. No mutations were found in coding regions of the StAR gene. Analysis of CYP11A-coding regions identified a G-->A change in exon 3, resulting in a Val(179)Ile missense mutation. This mutation was found in 1 of 29 patients studied and was not present in 50 controls. Finally, analysis of DAX-1 showed no variant in any of the women studied. In conclusion, mutations in StAR, SF-1, CYP11A, and DAX-1 are seldom found in hirsute patients and do not explain the steroidogenic abnormalities found in these women.

Adrenal Glands↗
PubMed2001

Characterization of mouse Atp6i gene, the gene promoter, and the gene expression.

Solubilization of bone mineral by osteoclasts depends on the formation of an acidic extracellular compartment through the action of a V-type ATPase. We previously cloned a gene encoding a putative osteoclast-specific proton pump subunit, termed OC-116 kDa, approved mouse Atp6i (ATPase, H+ transporting, [vacuolar proton pump] member I). The function of Atp6i as osteoclast-specific proton pump subunit was confirmed in our mouse knockout study. However, the transcription regulation of Atp6i remains largely unknown. In this study, the gene encoding mouse Atp6i and the promoter have been isolated and completely sequenced. In addition, the temporal and spatial expressions of Atp6i have been characterized. Intrachromosomal mapping studies revealed that the gene contains 20 exons and 19 introns spanning approximately 11 kilobases (kb) of genomic DNA. Alignment of the mouse Atp6i gene exon sequence and predicted amino acid sequence to that of the human reveals a strong homology at both the nucleotide (82%) and the amino acid (80%) levels. Primer extension assay indicates that there is one transcription start site at 48 base pairs (bp) upstream of the initiator Met codon. Analysis of 4 kb of the putative promoter region indicates that this gene lacks canonical TATA and CAAT boxes and contains multiple putative transcription regulatory elements. Northern blot analysis of RNAs from a number of mouse tissues reveals that Atp6i is expressed predominantly in osteoclasts, and this predominant expression was confirmed by reverse-transcription polymerase chain reaction (RT-PCR) assay and immunohistochemical analysis. Whole-mount in situ hybridization shows that Atp6i expression is detected initially in the headfold region and posterior region in the somite stage of mouse embryonic development (E8.5) and becomes progressively restricted to anterior regions and the limb bud by E9.5. The expression level of Atp6i is largely reduced after E10.5. This is the first report of the characterizations of Atp6i gene, its promoter, and its gene expression patterns during mouse development. This study may provide valuable insights into the function of Atp6i, its osteoclast-selective expression, regulation, and the molecular mechanisms responsible for osteoclast activation.

Adenosine Triphosphatases↗
PubMed2006

Autopsy and postmortem examination case study on genetic risk factors for cardiac death: polymorphisms of endothelial nitric oxide synthase gene Glu298Asp variant and T-786C mutation, human paraoxonase 1 (PON1) gene and alpha2beta-adrenergic receptor gene.

BACKGROUND/AIM: The Glu298Asp variant in exon 7 and T-786C mutation in the 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene, paraoxonase I gene (PON1), and alpha2beta-adrenergic receptor gene (alpha2beta-AR) have been reported to be genetic risk factors for coronary heart disease (CHD). The aim of this study was to investige the effects of these four genetic polymorphisms on the probability of death due to CHD, using data obtained from medico-legal autopsies. METHODS: Blood samples from three groups: healthy controls, dead cases with CHD and without CHD (the latter as a control for dead cases) were used. After DNA extraction, genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) test. RESULTS: The frequency of the T allele in Glu298Asp variant in the dead cases with CHD was significantly higher than that in the healthy control (p < 0.001, OR = 4.47) and that in the dead cases without CHD (p < 0.001, OR = 7.62). The gene frequency of PON1 was significandy different (p = 0.007) between dead cases with and without CHD, and was also significantly different (p = 0.025) between the healthy control and dead cases without CHD. The gene frequency of PON1 was not significantly different (p = 0.401) between the healthy controls and dead cases with CHD. Hence this gene was not associated with death due to CHD. The other polymorphisms (T-786C mutation, alpha2beta-AR) also showed no effect on death due to CHD. CONCLUSION: The polymorphism of Glu298Asp eNOS gene in dead cases may be useful for determining the cause of death in CHD cases in the Japanese population.

Adult↗
PubMed1994

The 5' flanking region of the rat beta 3-adrenergic receptor gene: divergence with the human gene and implications for species-specific gene expression.

beta 3-adrenergic receptor mRNAs exhibit species-specific expression (human vs. rodent) in distinct anatomical regions and appear to be expressed abundantly within rodent adipose tissue, but only at low levels within corresponding human tissues. In order to determine the genetic basis of the differential expression of the rat and human beta 3-adrenergic receptor genes, we cloned and sequence the rat gene and compared the 5' flanking regions of the two genes to identify potential discriminators in transcriptional regulation. We have found that the rat and human beta 3-adrenergic receptor 5' flanking regions are only 67% similar, unlike the close sequence similarity observed between the coding blocks (> 90%) and also observed between species for the 5' flanking regions of other beta-adrenergic receptor subtype genes (> 90%). In addition, the rat beta 3-adrenergic receptor gene lacks the four potential cAMP responsive elements identified within the 5' flanking region of the human receptor gene. The striking divergence in regulatory sequences between the rat and human beta 3-adrenergic receptor genes may potentially explain the differences in species-specific expression and tissue localization of the rat and human receptor mRNAs.

Animals↗
PubMed1992

The HLA class I gene family includes at least six genes and twelve pseudogenes and gene fragments.

We report the characterization of eight HLA class I homologous sequences isolated from cosmid and lambda libraries made from lymphoblastiod cell line 721 DNA. Four of these sequences, each contained within HindIII fragments of 1.7, 2.1, 3.0, and 8.0 kb, have class I homology extending over short intronexon regions. The remaining four are found within 7.5-, 8.0-, 9.0-, and 16.0-kb HindIII fragments, the first having homology to the 5' half of a class I gene whereas the latter three are homologous to the 3' portion of a class I gene. When combined with the characterization of other class I clones, this work brings the total number of HLA class I homologous sequences cloned and characterized to 18. Restriction mapping of cosmid clones showed that some of these sequences are linked to one another and to other class I pseudogenes and genes within 50-kb regions. Reconstruction experiments using the 18 class I genes and pseudogenes were performed that indicated that we had cloned all of the members of the HLA class I gene family detectable using HLA-A2 genomic DNA as probe. An additional 19th member of the class I gene family was identified using an HLA-E cDNA probe. Further Southern analysis with other class I probes indicated the 19 sequences comprise the entire class I gene family in LCL 721. Locus-specific probes were isolated from five of the eight clones and were used in Southern analysis of diverse genomic DNA to examine the polymorphism of the pseudogene sequences, demonstrating that some of them were highly polymorphic and some were missing entirely in certain haplotypes. An additional class I sequence, not contained within the 721 genome, was identified and may be found in association with the HLA-A11-Bw60 haplotype. Sequence comparisons were carried out to examine the evolutionary relationships among the pseudogenes. Hypothetical events in the evolution of the class I region are discussed.

Base Sequence↗
PubMed1992

Isolation of a novel human alpha (1,3)fucosyltransferase gene and molecular comparison to the human Lewis blood group alpha (1,3/1,4)fucosyltransferase gene. Syntenic, homologous, nonallelic genes encoding enzymes with distinct acceptor substrate specificities.

Biochemical and genetic evidence indicates that the human genome may encode four or more distinct GDP-fucose:beta-D-N-acetylglucosaminide 3-alpha-L-fucosyltransferase (alpha(1,3)fucosyltransferase) activities. Genes encoding two of these activities have been previously isolated. These correspond to an alpha(1,3/1,4)fucosyltransferase thought to represent the human Lewis blood group locus and an alpha(1,3)fucosyltransferase expressed in the myeloid lineage. We report here the molecular cloning and expression of a third human alpha(1,3)fucosyltransferase gene, homologous to but distinct from the two previously reported human fucosyltransferase genes. When expressed in transfected mammalian cells, this gene determines expression of a fucosyltransferase capable of using N-acetyllactosamine to form the Lewis x epitope, and alpha(2,3)sialyl-N-acetyllactosamine to construct the sialyl Lewis x moiety. This enzyme shares 91% amino acid sequence identity with the human Lewis blood group alpha(1,3/1,4)fucosyltransferase, yet exhibits only trace amounts of alpha(1,4)fucosyltransferase activity. Polymerase chain reaction analyses were used to demonstrate that the gene is syntenic to the Lewis locus on chromosome 19. These analyses also excluded the possibility that this DNA segment represents an allele of the Lewis locus that encodes alpha(1,3)fucosyltransferase but not alpha(1,4)fucosyltransferase activity. These results are consistent with the hypothesis that this gene encodes the human "plasma type" alpha(1,3)fucosyltransferase, and suggest a molecular basis for a family of human alpha(1,3)fucosyltransferase genes.

Alleles↗
PubMed1990

[Development of a new system for selection of A. foetidus transformed with foreign genes by using thymidine kinase gene as a marker and expression of HBsAg gene in A. foetidus].

A new system for selection of transformed Aspergillus foetidus was reported. In this system, TK- A. foetidus which were constructed by homologous recombination of mutated TK gene of vaccinia virus with TK gene of A. foetidus were screened by adding BUdR in agar plates. Conditions for screen of TK+ A. foetidus strain, transformation of A. foetidus and selection of transformed TK- A. foetidus have been studied. By using this system, several transformed A. foetidus which contained HBsAg gene derived bf a promoter H8 cloned from genomic DNA of A. foetidus were isolated. It was demonstrated that HBsAg gene was integrated into the chromosome DNA of A. foetidus by Southern blot after many passages of spores. ELISA showed that HBsAg was positive in the growth medium (p/n = 20). The 22 nm particles which were very similar to the HBsAg particles in human serum were found in the growth medium by immunoelectromicroscope. Western blot also gave the specific bands. All these data showed that HBsAg gene was expressed in A. foetidus and the products were secreted into the growth medium. The selection system using TK gene as marker could generally be used to study the expression of foreign gene in A. foetidus.

Aspergillus↗
PubMed1985

Chromosomal assignments of genes coding for components of the mixed-function oxidase system in mice. Genetic localization of the cytochrome P-450PCN and P-450PB gene families and the nadph-cytochrome P-450 oxidoreductase and epoxide hydratase genes.

Filter-hybridization studies show that major phenobarbital and pregnenolone-16alpha-carbonitrile-inducible cytochrome P-450 mRNAs in rats were encoded by members of separate, distinct gene families. These gene families are genetically divergent from each and show no cross-hybridization, even under low-stringency conditions. Furthermore, sequences contained in the P-450PB and P-450PCN gene families map to separate chromosomes of the mouse genome. Using mouse X Chinese hamster somatic cell hybrids (EBS cell lines), all distinguishable P-450PCN sequences were found to map to chromosome 6, whereas all P-450PB sequences were located on chromosome 7. Our data support the proposition that the region of the Coh locus on chromosome 7 is the site of the cytochrome P-450PB gene family. The presence of gene families for the cytochromes P-450 occurs in many mammalian species and is likely an important part of the mechanism by which the mixed-function oxidase system is capable of recognizing and metabolizing such a wide array of endogenous and foreign compounds. Conversely, NADPH-cytochrome P-450 oxidoreductase appears to be encoded in many vertebrate species by a single gene and is located on chromosome 6 of the mouse. Corroboratory data are presented to show that the Eph-1 locus on chromosome 1 is the site of at least one microsomal epoxide hydratase gene.

Animals↗