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Biomedical subjects

K Tanabe

Publications and source records attributed to K Tanabe.

At least 577 records · Page 32Linked to original sources
PubMed1981

Structural homology of DNA polymerase beta from various mammalian cells.

DNA polymerase beta was purified from various mammalian cells, i.e. mouse myeloma, rat liver, rat ascites hepatoma cells, rabbit liver, pig liver, and calf thymus cells. The apparent molecular weights of the polypeptides composing these enzymes were all about 40,000, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Moreover, tryptic peptide maps of these enzymes after radioiodination with 125I indicated that the molecular structures of the enzymes were basically identical. No difference was detected in the peptide maps of the mouse and rabbit enzymes, and only a few of the 22 spots in the fingerprint of the mouse enzyme were not detected in that of the rat enzyme. Furthermore, the peptide maps of DNA polymerase beta's from normal and malignant rat cells differed in only one spot.

Animals↗
PubMed1980

Chick embryo DNA polymerase beta. Purified enzyme consists of a single Mr = 40,000 polypeptide.

DNA polymerase (EC 2.7.7.7) beta was purified to near homogeneity from chick embryos. The final preparation has a specific enzyme activity of 1,100,000 units (nanomoles of dTMP incorporation/h) per mg of protein with (rA)n X (dT)12-18 as a template-primer. The molecular weight of DNA polymerase beta is about 40,000 as judged by gel filtration on Sephadex G-150 column. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the polypeptide of Mr = 40,000 accounted for 95% of total protein in the final preparation. The fingerprint analysis of tryptic peptides of polypeptide shows that 14 out of 24 125I-peptides from the Mr = 40,000 polypeptide are the same as those of the Mr = 40,000 polypeptide of DNA polymerase beta purified from rat ascites hepatoma cells. A Mr = 27,000 polypeptide, which was present in the less pure preparation, did not show any structure similar to Mr = 40,000 polypeptides from rat and chick cells. Thus, it is concluded that chick embryo DNA polymerase beta consists of a single polypeptide of Mr = 40,000. The minimal number of DNA polymerase beta molecules per chick embryo cell was estimated as about 5,000.

Animals↗
PubMed1980

Distinction between mouse DNA polymerases alpha and beta by tryptic peptide mapping.

Results presented here and in a previous paper (Tanabe et al. (1979) Biochemistry 18, 3401--3406) indicate that mouse beta-polymerase is a single polypeptide with an apparent molecular weight of 40,000. This polypeptide has now been analyzed by tryptic peptide mapping. Comparison of the results with identical analysis of mouse alpha-polymerase reveals that the tryptic peptides derived from the two enzymes are different. These results indicate that beta-polymerase is neither a subunit of alpha-polymerase nor a proteolytic degradation product of alpha-polymerase.

Animals↗
PubMed1980

Chromosome heteromorphisms in the Japanese. II. Nucleolus organizer regions of variant chromosomes in D and G groups.

The nucleolus organizer regions (NORs) of variant D- and G-group chromosomes characterized by enlargements of the short arms including secondary constrictions and satellites, were examined using the silver-staining method. Of a total of nine variants examined, four were found to have double Ag-stained NORs in the enlarged short arm, two were found to involve chromosome 22, one was a 13, and one, a 14. Four of the other variants had only one AG-stained NOR. From the positions of the NORs, three of them were judged to have enlarged satellites (two chromosomes 15 and 22) and the other an enlarged short arm (a 15). In the remaining variant (a 14), no Ag-stained material was noted in the short arm, so it could not be determined whether this variant chromosome was derived from the enlargement of the short arm or from satellites. Based on the position of the Ag-stained NORs and staining intensity of the Q and C methods in the short arms, mechanisms of producing the enlarged short arms of D- and G-group chromosomes are discussed.

Asian People↗
PubMed1980

Multiplication of Toxoplasma gondii in maturing erythroid cells.

Multiplication of Toxoplasma gondii was examined in vitro in murine erythroid cells at different stages of development. Toxoplasma gondii multiplied in nucleated erythroblasts and enucleated reticulocytes from the foetal liver, and in immature reticulocytes and yolk-sac derived erythrocytes from the foetal circulation. However, the rate of multiplication was lowered as erythroblasts matured, and multiplication was not detected in foetal erythrocytes. A decrease in the multiplication rate with maturation was also observed with yolk-sac erythrocytes.

Animals↗
PubMed1980

In vitro examination of LH-HCG receptors in human corpora lutea of the menstrual cycle and pregnancy.

Binding of 125I-human chorionic gonadotropin (HCG) to homogenates of the human corpora lutea of the menstrual cycle and pregnancy was examined in vitro. While corpora lutea of the menstrual cycle bound 125I-HCG specifically, the corpora lutea of pregnancy from 8 weeks' gestation bound little or none of the added 125I-HCG. In the corpus luteum of the menstrual cycle the dissociation constant for HCG and the number of binding sites were analyzed by a Scatchard plot. However, from these observations along with the findings of earlier reports, it may be suggested that LH-HCG receptors remain reduced in number in the corpus luteum of pregnancy.

Chorionic Gonadotropin↗
PubMed1980

Steady-state kinetics of mouse DNA polymerase alpha.

Steady-state kinetic studies of DNA polymerase alpha purified from mouse myeloma MOPC104E cells have been carried out. The results of initial velocity analysis with or without sodium pyrophosphate, a product inhibitor, indicated that the reaction mechanism of this enzyme can be categorized as an ordered Bi Bi type where the concentration of the ternary complex is very low.

Animals↗
PubMed1980

Penetration of chick embryo erythrocytes by toxoplasma gondii tachyzoites in simplified incubation media.

The ability of Toxoplasma gondii tachyzoites to penetrate chick embryo erythrocytes (CEE) and the extent of penetration were examined in various simplified, incubation media. Toxoplasma gondii penetrated CEE well in serum-free Eagle's minimum essential medium or in Hanks' balanced salt solution, but much less in phosphate buffered saline (PBS). However, the addition of glucose alone to PBS substantially increased the penetration. A similar effect was seen with other monosaccharides, except galactose. A further, marked increase in penetration was noticed if magnesium ion (but not calcium ion) was added to PBS containing glucose. The present results indicate that T. gondii can penetrate CEE well in simplified incubation solutions such as PBS only when magnesium ion and a monosaccharide are added. Their possible role is discussed in relation to cellular adhesiveness, because the adherence of the parasite to the host cell membrane may be the first step in the penetration process.

Animals↗
PubMed1979

Unique requirements for template primers of DNA polymerase beta from rat ascites hepatoma AH130 cells.

The optimal condition for the rat DNA polymerase beta activity with (rA)n . (dT)12-18 as a template-primer was determined. The activity was remarkably affected by the concentration of the primer, (dT)12-18' and the mixing ratio of (dT)12-18 to (rA)n. DNA polymerase beta requires higher primer concentration (Km = 11.1 microM with respect to 3'-OH of the primer) than DNA polymerase gamma (Km = 0.04 microM) or oncornaviral DNA polymerase (Km = 0.08 microM) and the enzyme represented the maximum activity in the base ratio of 2:1 with (dT)12-18 and (rA)n suggesting the difference in reaction mechanisms of these enzymes. Under the optimized conditions, the specific activity of the near homogeneous preparation of DNA polymerase beta was 1,000,000 units per mg protein.

Animals↗
PubMed1979

Steady-state kinetics of mouse DNA polymerase beta.

DNA polymerase beta from mouse myeloma has been purified to near homogeneity, and its properties have been examined. The enzyme did not catalyze a detectable level of dNTP turnover, pyrophosphate exchange, pyrophosphorolysis, 3'-exonuclease degradation, or 5'-exonuclease degradation. Steady-state kinetic studies point to an ordered bibi mechanism for the polymerization reaction. Metal activation, which is required for polymerization, did not alter the Km for either the dNTP or the template--primer.

Animals↗