Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A granulocyte-rich fraction was isolated from blood of a patient with chronic granulocytic leukaemia and from blood of a normal subject and the cells were disrupted in isotonic sucrose. The nuclei were removed by low-speed centrifugation and the post-nuclear supernatant was fractionated by centrifugation on sucrose density gradients. 2. The subcellular organelles in the gradients were detected with marker enzymes by the use of highly sensitive assay techniques. Similar results were obtained with granulocytes from both subjects. 3. Unsaturated vitamin B12-binding proteins were almost exclusively localized to the specific granules. Chromatographic analysis of these proteins showed them to have approximately equal proportions of transcobalamins I and III. Vitamin B12 assayed microbiologically could not be detected in the specific granule fractions.
Clin Sci Mol Med 1975 Aug
PMID:Analytical subcellular fractionation of human granulocytes with reference to the localization of vitamin B12-binding proteins. 23 84

1. Vitamin B12 absorption was measured in 18 patients with tropical malabsorption. 2. Absorption was particularly impaired in patients with severe mucosal lesions. 3. Sequential measurements with 57Co- and 58Co-labelled vitamin B12 were made before and 48 h after the start of tetracycline therapy. A rapid improvement (on average 22% increase in absorption) occurred in four of six patients with marked mucosal lesions. Further improvement occurred in four of five patients measured after 4 weeks' tetracycline, including the two who failed to improve initially. 4. These rapid changes in vitamin B12 absorption after antibiotics occur too early to be due to mucosal recovery and suggest that bacterial metabolism is an important factor in the malabsorption in these patients.
Clin Sci Mol Med Suppl 1978 Dec
PMID:Assessment of early and delayed responses in vitamin B12 absorption during antibiotic therapy in tropical malabsorption. 28 45

We have identified an anaerobically induced promoter for the cobalamin biosynthetic (cob) genes. In a plasmid the Cob promoter showed two of the three types of control of the intact chromosomal Cob operon: anaerobic induction and cAMP stimulation. Cobalamin repression was observed only in promoter fragments which included sequences far downstream of the transcription start site, suggesting that this control is post-transcriptional. One anaerobically induced transcript was identified and its 5' end was determined. Deletion mapping showed that 60 nucleotides upstream of the start site were sufficient for anaerobic synthesis of this transcript. Upstream of the transcription start site a putative sigma 70-dependent -10 recognition sequence was identified; however, no consensus -35 region was observed.
Mol Microbiol 1991 Jun
PMID:Analysis of an anaerobically induced promoter for the cobalamin biosynthetic genes in Salmonella typhimurium. 178 89

Transcobalamin II (TC II) deficiency is a rare autosomal recessive disease leading to cobalamin (Cbl; Vitamin B12) deficiency characterized by failure to thrive, megaloblastic anemia, impaired immunodefence and neurological manifestations. By means of Southern blotting and sequence analysis of TC II cDNA amplified from fibroblasts of an affected child and his parents, we have identified two mutant TC II alleles, one with a gross deletion and the other with a 4 nucleotide deletion. Both the mutations caused TC II mRNA and protein deficiency and hence defective plasma transport of Cbl and the development of Cbl deficiency in the affected child. The present study has identified molecular defects that cause TC II deficiency and lead to intracellular Cbl deficiency in humans.
Hum Mol Genet 1994 Oct
PMID:Identification of two mutant alleles of transcobalamin II in an affected family. 784 10

NF-kappa B and related factors are important transducers of external signals to the cell nucleus. They are abundant in the brain, where they may be significant for the regulation of gene transcription in plasticity-related processes for instance, via activation of protein kinase C. The subunit composition and levels of these factors in the mouse and rat brain and other tissues, using an assay based on gel retardation of the oligonucleotides corresponding to the kappa B DNA-element, are reported here. Three major kappa B-binding factors were observed. Factors I and II were activated by the dissociating agent deoxycholate. DNA protein cross-linking and antibody neutralization experiments suggest that factor I is a heterodimer of c-Rel and p65; factor II is a heterodimer of p50 and p65 (authentic NF-kappa B), and of p50 and c-Rel; factor III is the p50 homodimer (KBF1). All three factors were generally expressed in the 17-day-old rat embryo and 5-day-old pup, whereas in the adult rat, expression was more limited and showed certain tissue specificity. Factor II was the most generally expressed and the only factor observed in adult brain. Factor I was only detected in the adult testis whereas factor III was observed in the adult spleen and, in small amounts, in the liver and lung. Two minor kappa B-specific factors (A and B), distinctive to the brain and spleen, respectively, showed very slow gel mobility. Their estimated molecular weights were about 125 kDa and 95 kDa, respectively. Expression of factor A was stable in the rat brain during development. Factor A may be identical to a previously described brain-specific factor, BETA (Korner et al., Neuron, 3 (1989) 563-572). Thus, the expression pattern of kappa B-binding activities is apparently developmentally regulated and tissue-specific particularly in the adult. In the adult mouse and rat brain, only factors II (probably NF-kappa B and p50/c-Rel heterodimer) and A (probably BETA) could be observed.
Brain Res Mol Brain Res 1993 Oct
PMID:NF-kappa B-like factors in the murine brain. Developmentally-regulated and tissue-specific expression. 825 75

The disposition of whole blood mono-to hexaglutamyl methylfolate and plasma homocysteine (HCY) was used to evaluate potential lesion sites in one-carbon metabolism which could be responsible for neural tube defect(NTD)-affected pregnancies. An isocratic high-performance liquid chromatographic system (HPLC) with photodiode array detection was used to quantify and speciate whole-blood methylfolate into mono-, di-, tri-, tetra-, penta-, and hexaglutamate forms. This technique was also used with off-line radioassay to identify nonmethyl whole-blood folates. Isocratic HPLC with fluorescence detection was used to quantify SBDF derivatized homocysteine in plasma. The study investigated blood from 11 women who had experienced a previous NTD-affected pregnancy and 11 controls of similar age and social class. No subjects were pregnant. HCY levels were significantly higher in NTD subjects (P = 0.0486, 95% CI-2.799,0.001 using the Mann-Whitney test), as was the ratio of known intracellular (tri-to hexaglutamyl) methylfolate compared to extracellular (mono- and diglutamyl) methylfolate (P = 0.0062 95% CI-0.543, 3.862 using the Mann-Whitney test). Vitamin B12, red cell folate, circulating total methylfolate, and circulating mono-to hexaglutamyl methylfolates showed no difference between population groups. The disposition between individual and cumulative glutamate chain lengths of methylfolate showed significant trends which differed between population groups: (i) total blood methylfolate (Glu1-6) appears to be utilized by N-5-methyltetrahydrofolate:homocysteine methyltransferase (MS) in control blood but not NTD blood, where it appears to accumulate following a 45-min incubation; (ii) whole-blood hexaglutamyl methylfolate (5CH3-H4PteGlus) becomes a larger proportion of the total blood methylfolate in NTD than in control populations; and (iii) the intermediate glutamate chains of methylfolate (Glu1-5) remain relatively constant as 5CH3-H4PteGlu6 accumulates in NTD but appear to increase linearly with 5CH3-H4PteGlu6 in controls. The significant elevation of HCY in the NTD population is associated with the increasing proportion of 5CH3-H4PteGlu6 relative to the total methylfolate, since, when corrected for HCY level, the proportion of 5CH3-H4PteGlus to total methylfolate is similar in NTD and control populations. These trends are consistent with a defect at the level of vitamin B12 dependent MS which "traps" folate at the 5CH3-H4PteGlus level.
Biochem Mol Med 1997 Jun
PMID:Risk of neural tube defect-affected pregnancy is associated with a block in maternal one-carbon metabolism at the level of N-5-methyltetrahydrofolate:homocysteine methyltransferase. 923 94

Enzymatic radical catalysis is defined as a mechanism of catalysis by which enzymes catalyze chemically difficult reactions by utilizing the high reactivity of free radicals. Adenosylcobalamin (coenzyme B12) serves as a cofactor for enzymatic radical reactions. The recent structural analysis of adenosylcobalamin-dependent diol dehydratase revealed that the substrate 1,2-propanediol and an essential potassium ion are located inside a (beta/alpha)8 barrel. Two hydroxyl groups of the substrate coordinate directly to the potassium ion which binds to the negatively charged inner part of the cavity. Cobalamin bound in the base-on mode covers the cavity to isolate the active site from solvent. Based on the three-dimensional structure and theoretical calculations, a new mechanism for diol dehydratase is proposed in which the potassium ion plays a direct role in the catalysis. The mechanisms for generation of a catalytic radical by homolysis of the coenzyme Co-C bond and for protection of radical intermediates from undesired side reactions during catalysis are discussed based on the structure. The reactivating factors for diol and glycerol dehydratases have been identified. These factors are a new type of molecular chaperone which participate in reactivation of the inactivated holoenzymes by mediating ATP-dependent exchange of the modified coenzyme for free intact coenzyme.
Cell Mol Life Sci 2000 Jan 20
PMID:Radical catalysis of B12 enzymes: structure, mechanism, inactivation, and reactivation of diol and glycerol dehydratases. 1094 84

Factor V Leiden and prothrombin G20210A are clinically relevant genetic risk factors for venous thrombosis. Analysis for both mutations is increasingly being performed on patients exhibiting hypercoagulability. The goal of the current study was to evaluate the performance of primer-engineered multiplex polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for the simultaneous detection of factor V Leiden and prothrombin G20210A. Primer-engineered multiplex PCR-RFLP methods for the detection of factor V Leiden and prothrombin G20210A from the medical literature were reviewed. A modified method was optimized in which both mutations generate HindIII RFLPs and the prothrombin amplicon contains an invariant HindIII recognition site to assess the completeness of endonuclease digestion. Digested amplification products were analyzed by agarose gel electrophoresis in a single gel lane and visualized by ethidium bromide. Primer-engineered multiplex PCR-RFLP was used to analyze 205 human genomic DNA samples whose factor V Leiden genotypes had been previously determined by MnlI PCR-RFLP. Complete concordance for factor V Leiden genotypes was observed between the two methods in the 205-sample cohort comprising 139 wild-type, 62 heterozygous mutant, and four homozygous mutant individuals. For prothrombin G20210A, primer-engineered multiplex PCR-RFLP identified 196 wild-type and nine heterozygous mutant individuals in the 205-sample cohort. To independently verify prothrombin genotypes, the nine heterozygous mutants and an additional 11 wild-type patient samples (representing 10% of patient samples) were subjected to DNA sequencing. Complete concordance was observed between DNA sequencing and primer-engineered multiplex PCR-RFLP results. In further validation, 123 of the DNA samples consisting of four heterozygous mutant and 119 wild type individuals were genotyped with the Invader Assay for Factor II (prothrombin G20210A). Results showed 100% concordance between the Invader Assay and primer-engineered multiplex PCR-RFLP. A primer-engineered multiplex PCR-RFLP based on single restriction endonuclease digestion has been evaluated and shown to simultaneously and accurately detect factor V Leiden and prothrombin G20210A mutations. The method is robust and readily adaptable to the clinical molecular diagnostic laboratory.
J Mol Diagn 2000 Aug
PMID:Analytical evaluation of primer engineered multiplex polymerase chain reaction-restriction fragment length polymorphism for detection of factor V Leiden and prothrombin G20210A. 1122 20

We have assessed the relationship between homocysteine, its thiol metabolites, specific folate coenzymes, and vitamin B12 according to the two main functionally relevant genotype-genotype categories that maintain the balance between homocysteine transsulphuration to cysteine, and homocysteine remethylation via folate dependent methionine biosynthesis, namely 2756A-->G-MS/66A-->G-MSR and 677C-->T-MTHFR/1298A-->C-MTHFR. We examined 152 individuals who were being treated for either thromboembolic (TE) or non-thromboembolic (non-TE) events. Chi2 test for linear trend in odds ratio provides reasonable evidence for an altered risk of thromboembolism within the range of compound MS/MSR genotypes encountered (wt/wt-->recessive/recessive) (p< or =0.05), but not within the same range of MTHFR/MTHFR genotypes. Logistic regression analysis of the risk for a TE event gave OR=0.49 (95% CI, 0.26-0.92; p=0.026) for 2756A-->G-MS, OR=1.08 (95% CI, 0.65-1.78) for 66A-->G-MSR, OR=1.19 (95% CI, 0.69-2.06) for 677C-->T-MTHFR and OR=0.98 (95% CI, 0.52-1.85) for 1298A-->C-MTHFR. When genotypes were examined individually, one-way ANOVA showed only 677C-->T-MTHFR (p=0.005 [TE]) and 2756A-->G-MS (p=0.005 [non-TE] and p=0.0006 [all subjects]) influence homocysteine. One-way ANOVA also showed that MTHFR/MTHFR compound genotype significantly influences TE homocysteine distribution (p=0.044), but no other variable. In MS/MSR, homocysteine distribution is not significantly affected in TE subjects, but approaches significance in non-TE individuals (p=0.062). However, the increased power obtained when all subjects are analysed demonstrates a significant influence of MS/MSR upon homocysteine distribution (p=0.008). Other significant influences of MS/MSR were on total cellular 5-methyl-H4folate in non-TE subjects (p=0.042) and vitamin B12 in TE subjects (p=0.018). Given the central role of vitamin B12 in MS/MSR activity, 5-methyl-H4folate and homocysteine were also looked at by vitamin B12 quartile, independent of genotype: Vitamin B12 quartile significantly affected homocysteine distribution in TE (p=0.013) but not non-TE individuals, with no effect on 5-methyl-H4folate distributions. Similarly, the prevalence of clinical phenotypes (p=0.013) and of 'high risk' 2756A-->G-MS wildtypes (p=0.039) was associated with the disposition of homocysteine/B12 in TE but not non-TE subjects. Overall, results indicate compound MS/MSR genotype is associated with risk for a TE event. This may be related to variation in activity of the functional enzymes coded for by polymorphic forms of compound MS/MSR, resulting in altered catalytic cycling of methylcobalamin/cob(I)alamin, which in turn influences Hcy (and total 5-methyl-H4folate). The effect on vitamin B12 is greater in TE than non-TE subjects. The compound MTHFR/MTHFR genotype also influences variation in Hcy in TE subjects, but seemingly without the same level of mediation by vitamin B12. These results are consistent with accepted paradigms and offer a plausible explanation for the effect and interaction of specific SNPs in the TE phenotype. The biological implications of the limited number of MTHFR/MTHFR mutant alleles that can coexist, usually no more than two, may be explained by the serious consequences to folate status that these genotype combinations precipitate. We show that lowering of all folate 1-C pools occurs in the rare ct/cc compound genotype, except for the 5,10-methenyl-H4folate pool, which expands. 5,10-methenyl-H4folate is the immediate product of 5,10-methylene-H4folate, which is likely diverted away from methionine biosynthesis via the aberrant MTHFR enzyme. Consequences for the methylation cycle may be severe, and in most cases lethal for the developing embryo, where methylation is required for dozens of critical processes, but particularly for maintaining DNA methylation patterns that are now known to regulate the expression of half the complement of human genes via CpG islands located in the 5' promotor region, or within the first few exons of the gene.
Mol Genet Metab 2003 Jul
PMID:Interaction between common folate polymorphisms and B-vitamin nutritional status modulates homocysteine and risk for a thrombotic event. 1285 26

A multi-site study to assess the accuracy and performance of the biplex Invader assay for genotyping five polymorphisms implicated in venous thrombosis was carried out in seven laboratories. Genotyping results obtained using the Invader biplex assay were compared to those obtained from a reference method, either allele-specific polymerase chain reaction (AS-PCR), restriction fragment length polymorphism (PCR-RFLP) or PCR-mass spectrometry. Results were compared for five loci associated with venous thrombosis: Factor V Leiden, Factor II (prothrombin) G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, and plasminogen activator inhibitor (PAI-1) 4G/5G. Of a total of 1448 genotypes tested in this study, there were 22 samples that gave different results between the Invader biplex assay and the PCR-based methods. On further testing, 21 were determined to be correctly genotyped by the Invader Assay and only a single discrepancy was resolved in favor of the PCR-based assays. The compiled results demonstrate that the Invader biplex assay provides results more than 99.9% concordant with standard PCR-based techniques and is a rapid and highly accurate alternative to target amplification-based methods.
J Mol Diagn 2004 May
PMID:Detection of genomic polymorphisms associated with venous thrombosis using the invader biplex assay. 1509 70


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