Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mosaicism 46,XX/46,XX,del(10)(p13)/47,XX, +r/47,XX,del(10)(p13), +r was found in the lymphocytes and the fibroblasts of a patient with the following : profound mental retardation; craniofacial dysmorphism with frontal bossing, fine eyebrows, a large hypoplastic nasal bridge, prognathism of the upper jaw, thick lips; a long and thin neck; congenital heart disease; skeletal malformations, with club feet; and hypotonia and lax ligaments. These malformations, compatible with the trisomy 10p syndrome, suggest that the supernumerary ring chromosome was composed of 10p material. An increase of HK1 and GOT1 activities was found. This is in favour of a partial trisomy of chromosome 10. The relative frequencies of the clones constituting the mosaic vary from tissue to tissue and with time.
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PMID:[46,XX/46,XX,del (10) (p13)/47,XX,+r/47,XX,del (10) (p13), + r mosaicism and partial trisomy 10p phenotype (author's transl)]. 31 77

A male patient with mental retardation and typical clinical features of 10p trisomy syndrome was found to have a duplication of the short arm of chromosome 10 attached to the short arm of the Y chromosome. Quantitative evaluation of nine red cell enzymes showed significantly increased activity levels of HK1 and, to a lesser extent, of PK, PGI, 6PGD, and G6PD. It is suggested that the HK1 locus may be in the 10pter leads to p12 region. The increased levels of HK1 could affect other erythrocyte metabolic pathways slowing down the physiological rate of cellular senescence and result in increased activity levels of other cell-age-dependent enzymes.
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PMID:Increased HK1 activity levels in the red cells of a patient with a de novo trisomy 10p: t(Y;10)(p11;p12). 46 60

The Ch 1 + 2 fraction has been marked by means of culture of Vibrio cholerae Ogawa HK1 on a synthetic medium containing leucine H3. The antigen distribution has been then studied before and after vaccination with the same non-marked antigen in normal and axenic mice, at the same time by the demonstration of radioactivity and radioimmunofluorescence in intestine, spleen, liver, kidney and thymus. Whichever the administration route, intestine and spleen are first stimulated, then more intensively with the second injection or ingestion. When administrated per os the fraction crosses the intestinal barrier and is fixed on the main lymphoid organs: intestine, spleen, thymus. After ingestion or injection into axenic mice, spleen is the first organ stimulated.
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PMID:[Animal study on radioactive antigenic fractions isolated from V.cholerae. I. The Ch 1 + 2 fraction]. 71 45

The sensitivity to gamma-rays of a hyperkinetic mutant (HK1), characterized by high metabolic activity, has been studied and compared with gamma-ray sensitivity of the wild-type Oregon-K. Radiation damage, as measured by the frequency of induced dominant lethals (DL) and sex-linked recessive lethals (SLRL), was more in HK1 as compared with Or-K. The maximal sensitivity differences for these parameters were observed in the first brood. Translocations, on the contrary, were in general fewer in the HK1 compared with Or-K. These results have been interpreted in terms of reduced repair of mutational lesions in the energy-stressed cells of KH1.
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PMID:Innate metabolic differences and mutagen sensitivity of Drosophila melanogaster. I. Radiosensitivity of hyperkinetic mutant. 80 7

A previous method for red cell fractionation by density gradient centrifugation, using a swing-out rotor, has been scaled up to deal with larger volumes of red cells. This method, involving the use of a zonal rotor, is described and has been applied to the study of the decay of hexokinase in the red cells of normal individuals. Hexokinase activity was seen to fall very rapidly in the young cells followed by a much more gradual decline in older cells. It is estimated that the mature red cell probably contains no more than 2-3% of the hexokinase activity originally present in the reticulocyte. An electrophoretic study showed a changing pattern of the isozymes HK1 and HK2 with increasing cell age. HK2 declines very rapidly in the early fractions whereas HK1 appears to decay more gradually.
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PMID:An examination of the age-related patterns of decay of the hexokinases of human red cells. 120 20

An electrophoretic system which gives a clear separation of human hexokinases HK1, HK2 and HK3 is described. The distribution of the hexokinase isozymes in various human tissues, both adult and fetal, is reported. Some properties of the isozymes were investigated. HK2 was found to be more thermolabile than HK1, and there was also a small but significant difference in molecular size. Unlike HK3, HK1 and HK2 are not inhibited by high glucose concentrations. Screening of red cell lysates from 800 unrelated European individuals revealed no genetic variants of HK1 and HK2. However, in view of their difference in properties, it seems probable that the HK1 and HK2 isozymes are determined by separate gene loci.
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PMID:An electrophoretic study of the distribution and properties of human hexokinases. 123 74

The proportion of hexokinase (HK; EC 2.7.1.1) isozyme 1 (HK1) that is bound to the outer mitochondrial membrane is tissue specific and developmentally regulated. HK activity is known to be markedly elevated in many cancer cells and a significant fraction is mitochondrial bound. This study examined the role of the 15-amino acid N-terminal domain of HK1 in binding to liver and hepatoma mitochondria. A chimeric reporter construct, pCMVHKCAT, encoding this HK1 domain coupled to the chloramphenicol acetyltransferase (CAT) gene was electroporated into mouse Hepa 1-6 hepatoma cells. After digitonin treatment, cell fractions were assayed for HK, lactate dehydrogenase, and CAT activities. Digitonin (75 micrograms/mg of protein) caused cytosolic leak but 70% of HK remained with the pellet. HKCAT, like HK, remained predominantly with the pellet; CAT form the control, pCMVCAT, remained mostly unbound. Binding of membrane-free cell extracts to rat liver mitochondria in vitro showed 91% of the HKCAT bound, whereas only 12% of CAT bound. Specificity of HKCAT binding to mitochondria was demonstrated by competition of HK1 for HKCAT binding sites on rat liver mitochondria as well as by blockage of HKCAT binding by N,N'-dicyclohexylcarbodiimide, which covalently binds to porin and blocks HK1 binding. Deletional mutant constructs of HKCAT showed reduced binding with increasing deletion size. In summary, these studies demonstrate that the 15-amino acid N-terminal domain of HK1 is necessary and sufficient to confer mitochondrial binding properties to CAT and that there is specificity for this binding to the mitochondria.
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PMID:Targeting of hexokinase 1 to liver and hepatoma mitochondria. 130 5

The ompB operon encodes OmpR and EnvZ, two proteins that are necessary for the expression and osmoregulation of the OmpF and OmpC porins in Escherichia coli. We have used in vitro and in vivo experiments to show that cyclic AMP and the cyclic AMP receptor protein (CRP) directly regulate ompB. ompB expression in an ompB-lacZ chromosomal fusion strain was increased two- to fivefold when cells were grown in medium containing poor carbon sources or with added cyclic AMP. In vivo primer extension analysis indicated that this control is complex and involves both positive and negative effects by cyclic AMP-CRP on multiple ompB promoters. In vitro footprinting showed that cyclic AMP-CRP binds to a 34-bp site centered at -53 and at -75 in relation to the start sites of the major transcripts that are inhibited and activated, respectively, by this complex. Site-directed mutagenesis of the crp binding site provided evidence that this site is necessary for the in vivo regulation of ompB expression by cyclic AMP. Control of the ompB operon by cyclic AMP-CRP may account for the observed regulation of the formation of OmpF and OmpC by this complex (N. W. Scott and C. R. Harwood, FEMS Microbiol. Lett. 9:95-98, 1980).
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PMID:Positive and negative control of ompB transcription in Escherichia coli by cyclic AMP and the cyclic AMP receptor protein. 131 90

OmpR is a DNA-binding protein that regulates transcription of ompF and ompC. The activity of OmpR is controlled by the inner membrane osmosensor, EnvZ. In order to study the signaling process between EnvZ and OmpR, we analyzed two different envZ strains: the envZ473 strain, in which OmpC is constitutively produced and OmpF is fully repressed, and the envZ3 strain, in which the production of OmpC is greatly reduced and OmpF is not fully repressed by high-osmolarity growth conditions. Using direct sequencing of DNA derived from the polymerase chain reaction amplification method, we identified the mutation in the envZ473 strain as a Val-241-to-Gly substitution and the mutation in the envZ3 as an Ala-219-to-Val substitution. The relative DNA-binding affinity of OmpR derived from the envZ473 strain was dramatically increased for the upstream sequence of both ompF and ompC. In contrast, OmpR derived from the envZ3 strain was not converted to the high-affinity form. The intracellular levels of OmpR-phosphate, as analyzed by the in vivo phosphorylation approach, significantly increased in the envZ473 strain, while in the envZ3 strain the levels were considerably reduced, relative to those found in the parent strain. The intracellular level of OmpR protein in the envZ473 strain was also found to be markedly elevated relative to that of the parent strain. These results are discussed in relation to the role of phosphorylation and relative DNA-binding affinity of OmpR in the expression of ompF and ompC.
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PMID:Molecular analysis of the signaling pathway between EnvZ and OmpR in Escherichia coli. 131 Dec 95

OmpR is a transcriptional activator for the expression of outer membrane porin genes ompF and ompC in Escherichia coli. Its C-terminal half has been identified as the DNA-binding domain (K. Tsung, R. Brissette, and M. Inouye, J. Biol. Chem. 264:10104-10109, 1989). Recent studies have indicated that the N-terminal non-DNA-binding domain of OmpR is involved in modulating OmpR function through interaction with the EnvZ protein, a kinase and phosphatase for OmpR. We isolated and characterized two mutations, G94D and E111K, in the N-terminal domain of OmpR and one mutation, R182C, in the DNA-binding domain of OmpR. All three mutations abolished the ability of OmpR to bind to the ompF and ompC promoters in vivo, thus giving an OmpF- OmpC- phenotype. The decreased DNA-binding ability of the mutant OmpRs was not due to diminished phosphorylation of their N termini, since all the mutant OmpRs were found to be normally phosphorylated by EnvZ in vitro. The mutant OmpRs produced from multicopy plasmids were also found to inhibit completely the production of OmpF and OmpC in wild-type cells, and the complete inhibition depended on the function of EnvZ which was produced in cis or in trans from plasmids. The relationship of the possible alterations in OmpR by the mutations with the observed diminished binding ability is discussed.
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PMID:Mutations in a central highly conserved non-DNA-binding region of OmpR, an Escherichia coli transcriptional activator, influence its DNA-binding ability. 132 Nov 17


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