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E V Pankratova

Publications and source records attributed to E V Pankratova.

14 recordsLinked to original sources
PubMed1998

Oct-1 promoter region contains octamer sites and TAAT motifs recognized by Oct proteins.

The 5'-upstream region (1.3 kb) of the gene encoding the POU domain transcription factor Oct-1 was cloned and sequenced. CAT reporter gene analysis of this region has detected a functionally active promoter. This region contains 24 TAAT-core sites, arranged in five clusters (four to six sites in one cluster); two octamer sites (ATGCAAAT) are located in the first and second clusters; in the second one the CCAAT-box adjacent to the octamer overlaps with the TAAT-core site. As shown by gel retardation assay, Oct-1, Oct-2, and some unknown proteins from myeloma cell line NS/0 interact with the TAAT-core sites of these clusters. The results suggest autoregulation of Oct-1 gene expression that may also be controlled by other POU proteins, homeodomain proteins and CCAAT trans-action factors.

Animals↗
PubMed1997

Cysteine 50 of the POU H domain determines the range of targets recognized by POU proteins.

The best target of POU proteins (Oct-1, Oct-2) is an octamer sequence ATGCAAAT. POU proteins also recognize, with weaker affinity, the TAAT-like targets of another group of regulatory factors, the homeoproteins. Up to now, it has not been known why Cys50 of the POUHdomain is absolutely conserved in contrast to that in homeoproteins. To assess the importance of Cys50 in determining the binding specificity of POU proteins, all possible amino acids were substituted for Cys at position 50, and the resulting mutants were tested with probes containing octamer (ATGCAAATNN) or homeospecific binding sites. Only the wild-type POU was shown to adequately discriminate between the octamer and homeospecific sites, and the protein affinity was only slightly affected by the nucleotide sequence flanking the octamer at the 3'-end. Any amino acid substitution at position 50 resulted in the mutant protein binding efficiently both to the octamer and the TAAT-like sequences. Moreover, in this case the 3'-flanking sequences influenced the binding to a much greater extent.

Binding Sites↗
PubMed1994

Cell differentiation in vitro and the expression of Oct-2 protein and oct-2 RNA.

Expression of the oct-2 gene was studied in mouse tissues and during in vitro differentiation of embryocarcinoma PCC4, mouse neuroblastoma Neuro2A and NB41A3 cells in the presence of retinoic acid (RA) or 1% DMSO. oct-2 mRNA is characterized by a complex pattern and exists in both poly(A)+ and poly(A)- forms. oct-2 mRNA was found in many cell lines, whereas Oct-2 protein was detected only in some of these cells. oct-2 expression also changed during cell differentiation. The cell differentiation is likely to be controlled not only at the gene transcription level, but also at the level of regulation of nuclear transcription factor activity. Such a regulatory mechanism would provide for a finer regulation of cell differentiation.

Animals↗
PubMed1993

Utilization of the MHC class I (H-2Kb) purified molecule and its synthetic peptides for inhibition of Kb-specific suppressor T cells and their induction in vivo by the MHC peptides.

Six synthetic peptides of the MHC class I molecule corresponding to individual H-2Kb participants in amino acid sequences of domains alpha 1 (peptide 1 and 2) and alpha 2 (peptides 3, 4, 5, 6) were selected. Kb-specific suppressor T cells (Ts) were induced in vivo in mice, then pretreated with a set of peptides and assayed by proliferation decrease in a three-cell lymphocyte culture (MLC). The effector function of Ts was abolished by the complex of the alpha 2-domain peptides (but not by the alpha 1-domain peptides) and decreased by particular peptides separately (4, 5, 6) of the alpha 2-domain. Both alpha 1- and alpha 2-domain peptides, added in high concentration, decreased otherwise efficient enrichment of Ts during the absorption-elution procedure on the syngeneic macrophage (M psi) monolayers. A similar significant effect was observed using the purified Kb molecule (100 micrograms/ml) in the allogeneic M psi monolayer. Interaction between Ts receptors and some MHC peptides indicates in effector Ts activation in vivo by induction with peptides 5 and 6 of the alpha 2-domain. The fine mechanisms of interaction between MHC class I molecule epitopes and T-cell receptors of each of the T-cell subsets separately are presently being studied.

Amino Acid Sequence↗
PubMed1987

Extracellular portions of HLA antigens are not compact globulae.

Membranes of human spleen cells were hydrolyzed by papain and the extracellular portions of HLA antigen molecules isolated by monoclonal antibodies fixed on Sepharose. The isolated proteins were spin-labeled by TEMPO-dichlorotriazine. The values of rotational correlation times (tau) of spin-labeled proteins were calculated using dependencies of magnetic parameters found from ESR spectra vs viscosity at constant temperature. The tau-values were equal to 8 nsec for class I molecules and 14 nsec for class II molecules. These values were significantly lower than those predicted for a rigid sphere with dimensions equal to the extracellular portions of HLA molecules (20 nsec). This fact suggests the existence of flexibility in poly-functional HLA molecules, which seems to be important for their biological activity. In this respect, extracellular portions of HLA molecules resemble flexible Fc fragments (tau = 12 nsec) and differ from rigid Fab fragments (tau = 20 nsec) of immunoglobulins G. The rotation of the oligosaccharide chains attached to HLA molecules is restricted.

Chemical Phenomena↗
PubMedDate not supplied

[Intramolecular mobility of human major histocompatibility complex protein. A spin-label study].

Membranes of human splenocytes were hydrolyzed by papain and extracellular portions of class I and class II HLA antigen molecules were isolated by monoclonal antibodies fixed on Sepharose 4B. The isolated proteins were spin-labeled by TEMPO-dichlorotriazine and the values of rotational correlation times (tau) of labeled proteins were found using dependencies of ESR spectra parameters vs viscosity at constant temperature. The tau-values were equal to 8 ns for class I molecules and 14 ns for class II molecules. These values are 2-3 times lower than predicted for a rigid ellipsoid with mol wt. 50 kDa (about 20 ns). This fact suggests the existence of flexibility of HLA molecules which seems to be important for their biological activity. In this respect extracellular portions of HLA antigen molecules resemble flexible Fc fragments (tau = 12 ns) and differ from rigid Fab fragments (tau = 20 ns) of immunoglobulins G. The values of tau of spin-labeled proteins adsorbed from membrane hydrolysates on IgG-column was equal to 6.5 ns. The proteins adsorbed on lentil lectin column (after isolation of HLA proteins) have the tau-values equal to 9 ns.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[Colorimetric method of sequential determination of several dehydrogenases in a smear of human leukocytes].

Activity of several dehydrogenases was estimated by means of sequential incubation of a smear of human leukocytes in various media containing specific substrates for each enzyme and p-nitrotetrazolium violet as an acceptor of electrons. Photometry of the coloured products of redox reactions was carried out in the photoelectrocolorimeter, which was used for registration of steady state kinetics of all the reactions studied under usual conditions. Relative activity of succinate-alpha-glycerophosphate dehydrogenases and NADH/alpha-glycerophosphate dehydrogenases was estimated with an error of 2-4% in individual donors, while deviations of these values in leukocytes of the donors constituted +/- 15% as compared with their middle level calculated in 32 donors.

Colorimetry↗
PubMedDate not supplied

[Use of a series of synthetic peptides and purified major histocompatibility complex I (H-2K(b)) molecules for inhibiting T-suppressors, specific for the K(b) molecule, and their induction by peptides in vivo].

Six synthetic peptides of the MHC class 1 molecule corresponding to individual H-2kb participants in amino acid sequences of domains alpha 1 (peptide 1 and 2) and alpha 2 (peptide 3, 4, 5, 6) were selected. Kb-specific suppressor T cells (Ts) were in vivo in mice, then pretreated with a set of peptides and assayed by proliferation decrease in the third-partial mixed lymphocyte culture (MLC). Effector function of Ts was abolished by the complex of the alpha 2-domain peptides (but not by the alpha 1-domain peptides) and decreased by each peptide (4, 5, 6) of the alpha 2-domain. Both alpha 1 and alpha 2 domain peptides, added at high concentrations, decreased the otherwise efficient enrichment of Ts during the absorption-elution procedure on the syngeneic macrophage (MP) monolayers. A similar significant effect was observed the purified Kb molecule (100 mg/ml) on the allogeneic MP monolayer. Interaction between Ts receptors with some MHC peptides indicates effector Ts activation in vivo by induction with peptides 5+6 of the alpha 2 domain. The fine mechanisms of interaction between MHC class I molecule epitopes and T cell receptors (TCR) of each of the T cell subsets separately are under study now.

Amino Acid Sequence↗
PubMedDate not supplied

[Expression of the Oct-2 protein during cell differentiation in vivo and in vitro].

The expression of an Oct-binding protein Oct-2 was studied during differentiation of three cell lines. Two inductors were used in our experiments: retinoic acid and DMSO. It was shown that all these cells have heterogeneous population of Oct-2 mRNA. Under differentiation the pattern of Oct-2 RNA and expression of active Oct-2 proteins was changed.

Animals↗
PubMedDate not supplied

[Sensor for rapid measurement of blood glucose].

Bacterial biosensor consisting of Gluconobacter oxydans cells immobilized on the surface of oxygen electrode was used for measuring glucose concentration in human blood serum. The results were compared with those of standard clinical method (color reaction with ortho-toluidine). The proposed biosensor permits highly accurate measurements (mean quadratic deviation no more than 2% of the mean arithmetic), the coefficient of correlation with the results of standard method being 0.970.

Acetobacteraceae↗