Purification of mammalian glycinamide ribonucleotide (GAR) synthetase.
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Acyltransferases↗
Biomedical subjects
D Patterson
Publications and source records attributed to D Patterson.
Regional assignment of human liver-type 6-phosphofructokinase to chromosome 21q22.3 by using somatic cell hybrids and a monoclonal anti-L antibody.
The three structural loci encoding human phosphofructokinase, a key regulatory enzyme of glycolysis, are located on separate chromosomes. The gene coding for the liver-type subunit PFKL has previously been assigned to chromosome 21. We have used a subunit- and human-specific monoclonal antibody to liver PFK to detect the expression of human PFKL in hamster X human hybrid cell lines. A cell line carrying an 8;21 translocation which contains all of chromosome 21 except the band 21q22.3 was negative for the expression of PFKL whereas cell lines carrying the reciprocal 8;21 translocation were positive. In addition, a cell line with a ring chromosome 21 containing a breakpoint which excluded the distal part of the q22.3 band was negative for expression of PFKL. These results indicate that human PFKL is located on chromosome 21q22.3.
Animals↗
Fractionation of large mammalian DNA restriction fragments using vertical pulsed-field gradient gel electrophoresis.
A new design for pulsed field gradient (PFG) gel electrophoresis of large (greater than 50 kb) DNA fragments is described. The method eliminates distortion of migration of DNA because of the geometry of the applied electric field, requires a single power supply and a simple switching device, and is extremely simple to use. Parameters investigated include variation in pulse time, conditions of restriction enzyme digestion and DNA concentration, and the use of different restriction endonucleases. The method has been applied to restriction enzyme digested mammalian DNA from Chinese hamster and human/Chinese hamster hybrid sources and has allowed examination of the minimum separation of two DNA markers known to be on the same human chromosome, chromosome 21.
Animals↗
Variation of glycinamide ribonucleotide synthetase levels during in vitro aging of human fibroblasts: implications for gene dosage studies.
The levels of glycinamide ribonucleotide synthetase were monitored in four human fibroblast cell lines, two diploid, one monosomy 21 and one trisomy 21, from early passage number to senescence. In all four lines, enzyme activity increased as the cells aged. Enzyme levels for the diploid versus trisomy 21 cells did not consistently exhibit the expected gene dosage effect.
Aging↗
Human chromosome 21-encoded cDNA clones.
We have employed two strategies to isolate random cDNA clones encoded by chromosome 21. In the first approach, a cDNA library representing expressed genes of WA17, a mouse-human somatic cell hybrid carrying chromosome 21 as its sole human chromosome, was screened with total human DNA to identify human chromosome 21-specific cDNAs. The second approach utilized previously characterized single-copy genomic fragments from chromosome 21 as probes to retrieve homologous coding sequences from a human fetal brain cDNA library. Six cDNA clones on chromosome 21 were obtained in this manner. Two were localized to the proximal long arm of chromosome 21, two to the distal portion of the long arm, and one to the region of 21q22 implicated in the pathology of Down syndrome.
Chromosome Mapping↗
Two Drosophila melanogaster mutations block successive steps of de novo purine synthesis.
Drosophila melanogaster purine auxotrophs ade2(1) and ade3(1) have been characterized biochemically. The ade2(1) strain is deficient in the fourth step of the de novo purine synthetic pathway catalyzed by phosphoribosylglycinamidine synthase (phosphoribosylformylglycinamide amidotransferase). The ade3(1) strain is deficient in the previous step catalyzed by phosphoribosylglycinamide formyltransferase (GART). The mutation responsible for the slightly leaky ade3(1) phenotype was characterized further. First, the mutant GART polypeptide was found to be of normal size and present at normal levels. Second, the GART-encoding region of the mutant was cloned, inserted into a yeast-Escherichia coli shuttle vector, and used to transform mutant yeast. Transformants showed very slight in vivo activity when compared to wild type, verifying that the mutation is in the GART coding sequence. Lastly, the region of the gene encoding GART activity from mutant and inbred parental strain flies was completely sequenced. A single base transition was found, leading to the substitution of a serine for a highly conserved glycine. These two mutations provide examples of blocks in the de novo purine synthetic pathway in a whole animal.
Acyltransferases↗
Multiple purine pathway enzyme activities are encoded at a single genetic locus in Drosophila.
The Drosophila melanogaster Gart locus, known from previous work to encode the enzyme activity phosphoribosylglycinamide formyltransferase (GART), specifies two alternatively processed mRNAs and two proteins. We introduced the entire Gart locus into a Drosophila tissue culture cell line in which the locus is active. The resulting cell clones contained numerous copies of the locus and overproduced both mRNAs and both expected proteins, thus markedly facilitating analysis of these molecules. We assayed extracts of the clones for the activities of 10 enzymes important for de novo purine synthesis and found that, in addition to GART, two other purine pathway activities, phosphoribosylamine-glycine ligase (phosphoribosylglycinamide synthetase, GARS) and phosphoribosylformylglycinamidine cyclo-ligase (phosphoribosylaminoimidazole synthetase, AIRS), are similarly overproduced. All three activities are present together on the larger overproduced protein. A smaller protein appears to possess only GARS activity. Therefore, alternative mRNA processing can allow cells to produce enzyme activities in forms that are either linked or unlinked to other activities.
Acyltransferases↗
The 724 family of DNA sequences is interspersed about the pericentromeric regions of human acrocentric chromosomes.
We describe the organization of the complex, interspersed 724 family of DNA sequences that is distributed in multiple copies about the pericentromeric region of human acrocentric chromosomes. 724 family members were isolated using an efficient recombination-based assay for nucleotide sequence homology to screen a human genomic library. Eight related but distinct 724 family members were isolated that hybridized to a total of 20 different human-genomic EcoRI DNA fragments spanning 100,000 base pairs. In contrast with tandemly clustered satellite and ribosomal DNA sequences also located on the short arms of human acrocentric chromosomes, 724 family members are interspersed. No evidence for local interspersion or homology between 724 family members and ribosomal or satellite DNA sequences was found. Juxtaposition of the complex 724 family to the nucleolus organizer region was a recent event in primate evolution. The unique organization of 724 family members on each of the five human acrocentric chromosomes indicates that the 724 family continues to evolve within the human karyotype.
Base Composition↗
Secretory cells in the nucleus pulposus of the adult human intervertebral disc. A preliminary report.
A light microscopical study was conducted to ascertain the type of cells in the nucleus pulposus of the adult human intervertrebral disc. Three lumbar intervertebral discs were removed from each of 15 male and female adults at autopsy (ages ranged from 19 to 62 years). The tissue was fixed in formalin, decalcified in formic acid, dehydrated in a graded series of ethanol, embedded in paraffin, and serially sectioned at 7-10 micron. Tissue sections were affixed to albuminized glass slides and stained either by hematoxylin and eosin or hematoxylin and Van Gieson's stain. The cells of the bulk of the nucleus pulposus consisted of chondrocytes and a few fibroblasts; however, the subchondral matrix of the nucleus pulposos contained numerous stellate cells with (from 1 to 8) unusually long (up to 80 micron) primary cytoplasmic processes that often branch into secondary processes. The cell processes contained cytoplasmic varicosities at various intervals along their lengths; and their endings often expanded into bulbous, vesicle-filled process terminals. The surrounding extracellular matrix usually contained numerous, vesicle-filled, eosinophil matrix bodies. Morphological similarities of cytoplasmic varicosities, process terminals, and matrix bodies, as well as the apparent budding of process terminals, suggest that these previously unidentified cells are secreting an unknown matrix component into the subchondral matrix of the nucleus pulposus of the adult human.
Adult↗
Measurement of glycinamide ribonucleotide synthetase activity in intact human fibroblasts and Chinese hamster ovary cells.
An intact cell assay system based on Tween 80 permeabilization was used to investigate glycinamide ribonucleotide (GAR) synthetase activity in human fibroblasts and Chinese hamster ovary cells. Optimal conditions for the assay of the enzyme were determined with regards to ATP, MgCl2, NH4Cl and ribose-5'-phosphate concentrations as well as pH. Using the optimal assay conditions, the Vmax values as determined by Lineweaver-Burke double reciprocal plots were found to be 5.19 nmol GAR formed/5 X 10(5) cells/30 min for the fibroblasts and 13.4 nmol GAR formed/5 X 10(5) cells/30 min for the Chinese hamster ovary cells.
Adenosine Triphosphate↗
Community Health Affiliates of Ardmore, PA.
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Community Health Services↗
Regional localization of DNA sequences on chromosome 21 using somatic cell hybrids.
We have used a panel of Chinese hamster X human somatic cell hybrids, each containing various portions of chromosome 21 as the only detectable human chromosome component, for regional mapping of cloned, chromosome 21-derived DNA sequences. Thirty unique and very low-repeat sequences were mapped to the short arm and three sections of the long arm. Three unique sequences map to the proximal part of the terminal band 21q22.3, and five to the distal part of this band. Some of these may represent parts of gene sequences that may be relevant to the pathogenesis of Down syndrome, as 21q22 is the area required to be present in triplicate for the full clinical picture.
Animals↗
[Structure of the bone marrow stroma and hematopoiesis following chemotherapy in patients with acute myeloblastic leukemia].
Histometric methods were used to examine interrelations between hemopoiesis and bone marrow stroma in the trepanned iliac bones from 17 healthy subjects, 30 patients with acute myeloblastic leukemia and 6 patients at different times after chemotherapy. In health, young granulocytes were located endosteally, less frequently along the periphery of the vessels and around reticular cells. Erythro-normoblasts were mostly demonstrable perivascularly or near reticular cells and macrophages. During acute myeloblastic leukemia the interrelations under consideration were deranged. The significance of the endosteum in the regeneration of the stroma and hemopoiesis after cytostatic aplasia is demonstrated.
Adipose Tissue↗
Assignment of a third purine biosynthetic gene (glycinamide ribonucleotide transformylase) to human chromosome 21.
Using a series of human-hamster hybrid cell lines, a gene coding for glycinamide ribonucleotide transformylase was mapped to human chromosome 21. The availability of hybrids containing only portions of chromosome 21 allowed the gene to be assigned to the region between the q11.2 and the q22.2 bands, inclusive. Differentiation of human and hamster glycinamide ribonucleotide transformylase was accomplished via an immunoprecipitation assay that employed a polyclonal antibody raised against the human enzyme.
Acyltransferases↗
[Clinical importance of the results of cloning hematopoietic cells from patients with leukemias and hematopoietic dysplasias].
The authors describe the results of the cloning of hemopoietic cells from 85 patients with different patterns of nonlymphoblastic leukemias in the agar drop--liquid medium system. It is shown that measurement of the colony-stimulating activity of hemopoietic cells and their growth pattern as well as morphological study of the cultures can be employed in practical hematology for making diagnosis and differential diagnosis, for evaluation of the treatment efficacy and prediction of the disease prognosis. The presence of blast colonies, an increase in the number of cell aggregations is regarded as an unfavourable prognostic criterion. Elevation of the colony-stimulating activity of hemopoietic cells is evidence of a more favourable prognosis.
Clone Cells↗
A multifunctional protein possessing glycinamide ribonucleotide synthetase, glycinamide ribonucleotide transformylase, and aminoimidazole ribonucleotide synthetase activities in de novo purine biosynthesis.
Three activities on the pathway of purine biosynthesis de novo in chicken liver, namely, glycinamide ribonucleotide synthetase, glycinamide ribonucleotide transformylase, and aminoimidazole ribonucleotide synthetase, have been found to reside on the same polypeptide chain. Three diverse purification schemes, utilizing three different affinity resins, give rise to the same protein since the final material has identical specific activities for all three enzymatic reactions and a molecular weight on sodium dodecyl sulfate gels of about 110 000. A single antibody preparation precipitates all three activities and binds to the multifunctional protein obtained by two methods in Western blots. Partial chymotryptic digestion of the purified protein gives rise to two fragments, one possessing glycinamide ribonucleotide synthetase activity and the other containing glycinamide ribonucleotide transformylase activity.
Acyltransferases↗
The role of the c-mos gene in the 8;21 translocation in human acute myeloblastic leukemia.
The human c-mos proto-oncogene is located on chromosome 8 at band q22, close to the breakpoint in the t(8;21) (q22;q22) chromosome rearrangement. This translocation is associated with acute myeloblastic leukemia, subgroup M2. The c-myc gene, another proto-oncogene, has been mapped to 8q24. The breakpoint at 8q22 separates these genes, as determined by in situ hybridization of c-mos and c-myc probes. The c-mos gene remains on the 8q-chromosome and the c-myc gene is translocated to the 21q+ chromosome. Southern blot analysis of DNA from bone marrow cells of four patients with this translocation showed no rearrangement of c-mos.
Chromosome Mapping↗
5-Amino-4-imidazolecarboxamide riboside (Z-riboside) metabolism in eukaryotic cells.
Metabolites of 5-amino-4-imidazolecarboxamide riboside (Z-riboside) have potential roles in the regulation of cellular metabolism and as pharmacological agents in several pathological situations. Before studying Z-riboside metabolism it was necessary to develop methods for identifying and quantitating 5(4)-amino-4(5)-imidazolecarboxamide metabolites. These studies utilized Chinese hamster ovary fibroblast auxotrophic mutants to identify and isolate compounds relevant to Z-riboside metabolism by a combination of high performance liquid chromatographic procedures. In order to study Z-riboside metabolism wild-type and mutant cells were cultured in Z-riboside. This ribosyl precursor to a purine de novo intermediate does not undergo any detectable phosphorolysis but rather is phosphorylated by adenosine kinase in an unregulated manner. This results in the intracellular accumulation of 5-amino-4-imidazolecarboxamide ribotide (ZMP), the levels of which control flow from Z-riboside to the following metabolites: 1) IMP and other purine nucleotides, 2) 5-amino-4-imidazole-N-succinocarboxamide ribotide (sZMP), and 3) 5-amino-4-imidazolecarboxamide riboside 5'-triphosphate (ZTP). At low ZMP concentrations, the predominant metabolic fate is IMP. Initially, IMP enters the adenylate and guanylate pools, but subsequently is hydrolyzed to inosine and this phosphorolyzed to hypoxanthine. At intermediate ZMP concentrations there is net retrograde flux through the bifunctional enzyme adenylosuccinate AMP lyase resulting in sZMP synthesis and antegrade flux leads to the accumulation of adenylosuccinate. At high ZMP concentrations, ZTP accumulates. In addition to these effects on purine metabolism, pyrimidine nucleotide pools are depleted when ZMP accumulates. These results are discussed in relation to the regulation of purine nucleotide synthesis and the use of Z-riboside as a pharmacological intervention in pathophysiological situations.
Adenosine Monophosphate↗