Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A purification procedure for RNA polymerase from uninfected and phage SP01-infected Bacillus subtilis is presented. The RNA polymerase purified from B. subtilis 10 min after infection with wild type phage SP01 is resolved into two major fractions (B, C) and one minor fraction (A) by calf thymus DNA-cellulose chromatography. Fraction C is indistinguishable from RNA polymerase from uninfected cells with respect to transcription specificity (both before and after phosphocellulose chromatography). Fraction B yields, on subsequent phosphocellulose chromatography, an enzyme (B-P) whose properties distinguish it from the host RNA polymerase. Enzyme B-P preferentially transcribes SP01 DNA and selectively forms rapidly initiating complexes with SP01 DNA but not with heterologous DNA. The SP01 RNA synthesized by Enzyme B-P includes, as previously reported, a large proportion of asymmetrical middle viral RNA. Host RNA polymerase holoenzyme synthesizes asymmetrical early viral RNA, while host core polymerase synthesizes symmetrical RNA that is complementary to early, middle, and late in vivo viral RNA and contains a preponderance of antimessenger. The subunit composition of Enzyme B-P is identical to host core polymerase with respect to the beta,beta', and alpha subunits and two additional components of mr equals 9,500 and 11,000 that we observe in all preparations of RNA polymerase. In addition, Enzyme B-P has two subunits of mr equals 13,000 and 28,000, which are synthesized after phage infection. On heterologous template, Enzyme B-P and host core polymerase have comparable activities. On these templates, addition of host initiation factor, sigma, restores full activity to Enzyme B-P as well as to host core polymerase. Sigma also modifies the activity of Enzyme B-P on SP01 DNA, restoring some asymmetrical early RNA transcription while retaining some asymmetrical middle RNA transcription.
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PMID:RNA polymerase from phage SP01-infected and uninfected Bacillus subtilis. 80 88

An X isochromosome for the long arm was studied in 3 patients with Turner's syndrome using the BrdUrd-Hoechst 33258-Giemsa method and C-staining. In all 3 patients studied, the long arms of the i(Xq) were asymmetrical with respect to chronology of DNA synthesis. The most striking asynchrony of DNA replication was observed in large early replicating segments adjacent to the centromeric region. Two C bands of similar appearance were observed localized symmetrically in both arms. The data are interpreted in accordance with two possible origins of an abnormal X which is known as i(Xq).
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PMID:Isochromosome X in man: different DNA replication patterns in the long arms. 93 57

Experimental results on the transcription of Balbiani rings BR 1 and BR 2 of Chironomus thummi salivary gland chromosomes are presented. The DNA of Balbiani ring 2, which is the most active puff in larvae, is transcribed into large RNA molecules of about 22 X 10(6) D which resist degradation by heating, formamide or urea treatment. The asymmetrical distribution of electrophoretic profiles of BR 2 RNA and the appearence of a symmetrical BR RNA peak in the nucleoplasm suggest the synthesis of (mainly) one RNA fraction in BR 2. The gel electrophoretic patterns of BR 1 RNA are, on the other hand, characterized by the appearance of two main fractions of high molecular weight RNA, one of which corresponds in molecular weight (about 22 X 10(6) D) to BR 2 RNA. The second RNA fraction is significantly smaller in molecular size (molecular weight: about 10 X 10(6) D) and, like the 22 X 10(6) D RNA fractions of the two Balbiani rings, resistant against heating in 8 M urea. Binding to poly (U) sepharose of a significant part of Balbiani ring RNA suggests the existence of poly (A) and/or oligo (A) sequences in the Balbiani ring RNA. -- In situ hybridization of BR RNA to the salivary gland chromosomes reveals accumulation of silver grains over the Balbiani ring regions only and demonstrates the restriction of BR DNA sequences to the corresponding Balbiani ring.
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PMID:The transcripts of Balbiani rings from Chironomus thummi. Giant RNA molecules with messenger characteristics. 100 Nov 42

A number of parameters were measured in a series of 12 hybrid cell clones from Chinese hamster and mouse cells to test the hypothesis that asymmetrical chromosome loss may result from asynchrony in the replication of the two parental sets of chromosomes. All clones tended to lose telocentric (mouse) chromosomes with culture time, irrespective of the starting ratio of parental chromosomes, and in all clones, biarmed (hamster) chromosomes appeared to complete DNA replication slightly earlier than telocentrics. However, no quantitative correlation could be established between the degree of asynchrony in chromosome DNA replication and the extent of chromosome loss. It appeared that telocentric chromosomes were lost more readily from those clones which started with a high hamster-to-mouse chromosome ratio.
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PMID:Asynchronous DNA replication and asymmetrical chromosome loss in Chinese hamster-mouse somatic cell hybrids. 102 57

A model is proposed for the structure of stereospecific sites in regulatory proteins. On its basis a possible code is suggested that governs the binding of regulatory proteins at specific control sites on DNA. Stereospecific sites of regulatory proteins are assumed to contain pairs of antiparallel polypeptide chain segments which form a right-hand twisted antiparallel beta-sheet, with single-stranded regions at the ends of the beta-structure. The model predicts that binding reaction between a regulatory protein and double-helical DNA is a cooperative phenomenon and is accompanied by significant structural alteration at the stereospecific site of the protein. Half of hydrogen bonds normally existing in beta-structure are broken upon complex formation with DNA and a new set of hydrogen bonds is formed between polypeptide amide groups and DNA base pairs. In a stereospecific site, one chain (t-chain) is attached through hydrogen bonds to the carbonyl oxygens of pyramides and N3 adenines lying in one DNA strand, while the second polypeptide chain (g chain) is hydrogen bonded to the 2-amino groups of guanine residues lying in the opposite DNA strand. The amide groups serve as specific reaction sites being hydrogen bond acceptors in g-chain and hydrogen bond donors in t-chain. The single-stranded portions of t- and g-chains lying in neighbouring subunits of regulatory protein interact with each other forming deformed beta-sheets. The recognition of regulatory sequences by proteins is based on the structural complementarity between stereospecific sites of regulatory proteins and base pairs sequences at the control sites. An essential feature of these sequences is the asymmetrical distribution of guanine residues between the two DNA strands. The code predicts that there are six fundamental amino acid residues (serine, threonine, asparagine, histidine, glutamine and cysteine) whose sequence in stereospecific site determines the base pair sequence to which a given regulatory protein would bind preferentially. The code states a correspondence between four amino acid residues at the stereospecific site of regulatory protein with the two residues being in t- and g-segments, respectively, and AT(GC) base pair at the control site. It is thus possible to determine which amino acid residues in the repressor and which base pairs in the operator DNA are involved in specific interactions with each other, as exemplified by lac repressor binding to lac operator.
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PMID:[A code governing specific binding of regulatory proteins to DNA and structure of stereospecific sites of regulatory proteins]. 121 4

1. The properties of nascent DNA in the replicative closed circular mitochondrial DNA were examined in the in vitro system of discontinuous replication, using newborn rat liver mitochondria containing endogeneous DNA templates and enzymes. 2. The nascent DNA associated with the closed circular DNA fraction was found to be of two types; one class consisted of the fragments, and the other of the higher molecular-weight DNAs. Data from pulse and chase experiments indicate that the fragments were initially synthesized and subsequently converted into both heavy and light strands of the higher molecular-weight DNAs in an asymmetrical mode. 3. DNA - DNA hybridization experiments revealed that half of the fragments at least were copies of complementary parts of the parental DNA. 4. Based on the present in vitro data, a tentative structure of the replicating region and its expansion are discussed.
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PMID:Mode of extension of the daughter strands in the replication of closed circular mitochondrial DNA in vitro. 124 15

The Single Strand Conformation Polymorphism (SSCP) technique is widely used in mutation analysis. We have introduced several modifications to the SSCP method, which overcome the problem of incomplete denaturation or reannealing of DNA during electrophoresis. The modifications consist of asymmetrical PCR amplification of the sequence of interest, electrophoresis with a higher concentration of acrylamide, and the analysis of the DNA fragments under u.v. light. We have applied this method to the analysis of two specific diseases: neurofibromatosis type 1 (NF1) and cystic fibrosis (CF) from PCR amplified exons. Two single nucleotide changes were observed with this method.
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PMID:Mutation analysis of genetic diseases by asymmetric-PCR SSCP and ethidium bromide staining: application to neurofibromatosis and cystic fibrosis. 128 3

Recent reports have more precisely defined the distribution of somatic mutations around rearranged mouse V-D-J genes. The 5' boundary of mutation is most likely in the region of the transcription start site (cap) and/or the promoter (P), implying that transcription may be a prerequisite for mutations to be generated. As more than 95% of somatic mutations lie downstream of the cap site, the transcription unit itself is implicated as the target of the mutational machinery. For heavy chain genes, the 3' boundary can extend into the enhancer region (E). For kappa light chain genes, the 3' boundary extends to approximately 700 bp beyond J kappa-5 (approximately 700 bp upstream of E). In a single study on mutated derivatives of the rearranged mouse lambda 1 light chain V-J gene, it was claimed that the 3' boundary fell within the constant region (C) exon. Although more data are required, the frequency of mutations around V-D-J genes appears asymmetrical, being positively skewed with a single mode centred near the V-D-J coding region and a long tail extending into the 3' non-translated region of the J-C intron. Such a distribution may place constraints on possible molecular mechanisms. It is suggested that the apparent asymmetrical pattern of mutation is best explained by models that assume localized error-prone DNA synthesis generating variable fragment lengths of mutated DNA or cDNA retrotranscripts. The frequency distribution of these lengths of mutated DNA is positively skewed into the 3' J-C intron, with a common terminus at or near the cap site. It is then assumed that they can be integrated into the target V-D-J region via a gene conversion or homologous recombination process. The model invoking reverse transcription may be preferred as it best explains the data without too many ad hoc assumptions.
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PMID:Defining the nucleic acid substrate for somatic hypermutation. 139 73

Trans-specific evolution of allelic polymorphism at the major histocompatibility complex loci has been demonstrated in a number of species. Estimating the substitution rates and the age of trans-specifically evolving alleles requires detailed information about the alleles in related species. We provide such information for the chimpanzee DRB genes. DNA fragments encompassing exon 2 were amplified in vitro from genomic DNA of ten chimpanzees. The nucleotide sequences were determined and their relationship to the human DRB alleles was evaluated. The alleles were classified according to their position in dendrograms and the presence of lineage-specific motifs. Twenty alleles were found at the expressed loci Patr-DRB1, -DRB3, -DRB4, -DRB5, and at the pseudogenes Patr-DRB6, -DRB7; of these, 13 are new alleles. Two other chimpanzee sequences were classified as members of a new lineage tentatively designated DRBX. Chimpanzee counterparts of HLA-DRB1*01 and *04 were not detected. The number of alleles found at individual loci indicates asymmetrical distribution of polymorphism between humans and chimpanzees. Estimations of intra-lineage divergence times suggest that the lineages are more than 30 million years old. Predictions of major chimpanzee DRB haplotypes are made.
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PMID:Trans-species origin of Mhc-DRB polymorphism in the chimpanzee. 142 8

Three Down syndrome patients for whom karyotypic analysis showed a "mirror" (reverse tandem) duplication of chromosome 21 were studied by phenotypic, cytogenetic, and molecular methods. On high-resolution R-banding analysis performed in two cases, the size of the fusion 21q22.3 band was apparently less than twice the size of the normal 21q22.3, suggesting a partial deletion of distal 21q. The evaluation of eight chromosome 21 single-copy sequences of the 21q22 region--namely, SOD1, D21S15, D21S42, CRYA1, PFKL, CD18, COL6A1, and S100B--by a slot blot method showed in all three cases a partial deletion of 21q22.3 and partial monosomy. The translocation breakpoints were different in each patient, and in two cases the rearranged chromosome was found to be asymmetrical. The molecular definition of the monosomy 21 in each patient was, respectively, COL6A1-S100B, CD18-S100B, and PFKL-S100B. DNA polymorphism analysis indicated in all cases a homozygosity of the duplicated material. The duplicated region was maternal in two patients and paternal in one patient. These data suggest that the reverse tandem chromosomes did not result from a telomeric fusion between chromosomes 21 but from a translocation between sister chromatids. The phenotypes of these patients did not differ significantly from that of individuals with full trisomy 21, except in one case with large ears with an unfolded helix. The fact that monosomy of distal 21q22.3 in these patients resulted in a phenotype very similar to Down syndrome suggests that the duplication of the genes located in this part of chromosome 21 is not necessary for the pathogenesis of the Down syndrome features observed in these patients, including most of the facial and hand features, muscular hypotonia, cardiopathy of the Fallot tetralogy type, and part of the mental retardation.
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PMID:No significant effect of monosomy for distal 21q22.3 on the Down syndrome phenotype in "mirror" duplications of chromosome 21. 146 8


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