Biomedical subjects

M G Samsonova

Publications and source records attributed to M G Samsonova.

5 recordsLinked to original sources

PubMed1992

Conservative system for dosage-dependent modulation of translational fidelity in eukaryotes.

Variations in dosage of some genes can alter the level of translational fidelity. The Saccharomyces cerevisiae genes that act as dosage-dependent suppressors and/or modulators of suppression, are the following: some tRNA genes (for example, tRNA(Gln)) inducing readthrough by mispairing; genes coding for either translational elongation factor or other proteins taking part in translation; and some genes of unknown function. We suggest that the SUP35 protein is a factor which may play a major role in balance-dependent regulation of translational fidelity. Homologues of this genes have been identified in other yeast genera (Pichia), green algae (Chlamydomonas) and various animals including man. No homologies have been found in the polychaeta (Nereis) or in insects (Drosophila). Rates of evolution differ for two separate parts of the genes; the N-terminal part, which is important for ambiguous translation in Saccharomyces, is markedly variable in the organisms tested. However, the C-terminal part which is required for yeast viability has a common origin but a separate evolution from that of the EF-Tu protein family.

Animals↗

PubMed1991

Structure comparison and evolutionary relations between elongation factors EF-Tu (EF-1 alpha) and SUP 2 proteins.

On the basis of high homology and structural similarity, three genes, SUP2 Saccharomyces cerevisiae, SUP2 Pichia pinus and GST1 Homo sapiens, might be considered as members of one family named SUP2. Comparison of the primary structure of SUP2 proteins and elongation factors EF-Tu(EF-1 alpha) from 19 different species was performed. It was found that SUP2 proteins bear more homology to eukaryotic elongation factor than to procaryotic EF-Tu, though the degree of sequence conservation in SUP2 proteins is smaller than in EF-1 alpha factors. The extensive phylogenetic analysis of SUP2 and EF-Tu(EF-1 alpha) genes was performed by means of 3 methods, 2 phenetic and one cladystic (maximal parsimony). The data support the close relation of SUP2 genes to other elongation factor genes.

Amino Acid Sequence↗

PubMed1991

A new method for finding long consensus patterns in nucleic acid sequences.

We describe a fast computer algorithm for identifying consensus patterns in DNA sequences. The method requires no prior assumptions about the consensus pattern other than its length. In particular no previous knowledge of the frequency or spacing of consensus patterns is required. However, a priori information about the shape of the consensus pattern, or invariability of individual positions, or the overall conservation level, can be utilized to enhance the selectivity and sensitivity of search. As the number of all possible consensus words increases very rapidly with length, comprehensive searches have usually been restricted to a maximum of 10-12 nucleotides, even when large mainframes are used. Our algorithm enables searching for consensus patterns of this order on current mid-range and powerful microcomputers. Searches may be conducted on single, long sequences or a set of possibly aligned shorter sequences. We give examples of identified consensus patterns in both prokaryotic and eukaryotic DNA sequences, along with some typical program timings.

Base Sequence↗

PubMed1975

[Genetico-biochemical study of acid phosphatases in Saccharomyces cerevisiae yeast. V. Genetic control of regulation of acid phosphatase II synthesis].

Regulation of exocellular enzyme acid phosphatase 2 synthesis is studied. 21 mutants with consitutive synthesis of this enzyme are obtained by UV-irradiation. All mutants were recessive and were distributed among 3 complementation groups ACP80, ACP81, ACP82. Two groups, ACP80 and ACP81 corresponded to two different genes, which showed no linkage with ACP1, ACP2 and PHO1 genes. The type of synthesis of acid phosphatase 2 in strains acp1 acp80, acp1 acp81, acp2 acp80, acp2 acp81 is determined, and a conclusion is made about the participation of ACP2 gene in the regulation of acid phosphatase 2 synthesis. It is shown that some mutations in PHO1 gene, which block the activity of acid phosphatase 1, influence the activity and regulation of acid phosphatase 2.

Acid Phosphatase↗

PubMed1975

[Genetic-biochemical study of acid phosphatases from Saccharomyces cerevisiae yeasts. IV. Genetic control of acid phosphatase II activity].

Genetic control of exocellular acid phosphatase of yeast Saccharomyces cerevisiae (acph 2) is studied. 64 mutants with the impaired activity of acid phosphatase have been obtained by UV-irradiation. All the mutations have been distributed among 4 genes: ACP1, ACP2, ACP3, ACP4 using functional and recombinational tests for allelism. It is shown that mutations in genes ACP1--ACP3 are recessive, but in the gene ACP4--dominant. The gene ACP4 is found to be located 0.41+/-0.064 in strains from centromere and to have no linkage with ACP1. Possible functions of genes studied are under discussion.

Acid Phosphatase↗