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M Nagamine

Publications and source records attributed to M Nagamine.

At least 55 records · Page 3Linked to original sources
PubMed1986

Formation of the transcription initiation complex on mammalian rDNA.

Steps for the formation of transcription initiation complex on the human rRNA gene (rDNA) in vitro were analyzed with partially purified transcription factors and RNA polymerase I. The reaction requires at least two factors besides RNA polymerase I for maximal efficiency. Preincubation and short-pulse analyses of the accurate transcripts revealed the following steps. First, the species-dependent factor, designated TFID, bound to the rDNA template, forming a preinitiation complex (PIC-1) which was resistant to a moderate concentration (0.015 to 0.02%) of Sarkosyl. Other factors, designated TFIA and RNA polymerase I, were then added to convert it to the final preinitiation complex PIC-3. This complex incorporated the first two nucleoside triphosphates of the starting site to complete the initiation complex (IC), which was resistant to a high concentration (0.2%) of Sarkosyl. Binding of TFID was rate limiting in the overall initiation reaction in vitro. Together with the kinetics of incorporation, the results are interpreted to mean that TFID, one bound, remains complexed with rDNA together with TFIA as the PIC-2 for many rounds of transcription by RNA polymerase I. Thus, the formation of PIC-2 may be a prerequisite for the stable opening of rDNA for transcription in vivo.

Animals↗
PubMed1985

Presence of a limited number of essential nucleotides in the promoter region of mouse ribosomal RNA gene.

Point mutations are introduced into a mouse rDNA fragment containing the promoter region by a sodium bisulfite method and the mutants are tested for the ability of accurate transcription initiation in vitro. The results indicate that the change, G to A, at -7 completely eliminates the promoter activity, and those at -16 and at -25 decrease it to about 10% and 50%, respectively. On the other hand, the substitutions at +9, +4, -2, -9 and -39 do not alter the template activity significantly. It is concluded that there are limited but distinct nucleotides that are essential for the transcription initiation of this gene. This sort of absolute requirement for single specific bases is not reported in protein coding genes transcribed by RNA polymerase II. We propose that these rigid recognition signals which we have found are the molecular basis for the strong species-dependency of the transcription machinery of RNA polymerase I system. A model is presented in which a transcription factor interacts with the rDNA promoter from one side of the DNA double-helix with essential contacts at these bases.

Animals↗
PubMed1984

Occurrence of two forms of H2M2 isoenzyme of lactate dehydrogenase.

Serum from healthy human subjects and serum from animals demonstrated a splitting of the H2M2 isoenzyme fraction of lactate dehydrogenase (LDH) into two subbands on polyacrylamide gel electrophoresis. These subbands were designated H2M2-a and H2M2-b, based on their relative electrophoretic mobilities, with the H2M2-a band being more anodal. The doublet of the H2M2 band was also demonstrated in human erythrocytes and in the hybridization mixture from porcine LDH, indicating the production of two forms of H2M2 isoenzyme in tissues. Supportive evidence for the presence of two H2M2 subforms was obtained by ion-exchange chromatography of the hybridization mixture. The recombination experiments of LDH-binding IgA with both normal human serum and LDH M subunit variant serum indicated the difference of molecular structure between the two subforms. On the basis of the results obtained in this study, a theoretical model of the probable molecular structure of LDH isoenzymes is proposed which could account for both the occurrence of two subforms of H2M2 and their selective binding to LDH-linking IgA.

Animals↗
PubMed1984

Purification and properties of L-alanine:4,5-dioxovalerate aminotransferase from Chlorella regularis.

The enzyme L-alanine:4,5-dioxovalerate aminotransferase (EC 2.6.1.43), which catalyzes the synthesis of 5-aminolevulinic acid, was purified 161-fold from Chlorella regularis. The enzyme also showed L-alanine:glyoxylate aminotransferase activity (EC 2.6.1.44). The activity of glyoxylate aminotransferase was 56-fold greater than that of 4,5-dioxovalerate aminotransferase. The ratio of the two activities remained nearly constant during purification, and when the enzyme was subjected to a variety of treatments. 4,5-Dioxovalerate aminotransferase activity was competitively inhibited by glyoxylate, with a Ki value of 0.5 mM. Double-reciprocal plots of velocity versus 4,5-dioxovalerate with varying L-alanine concentrations indicate a ping-pong reaction mechanism. The apparent Km values for 4,5-dioxovalerate and L-alanine were 0.12 and 3.5 mM, respectively. The enzyme is an acidic protein having an isoelectric point of 4.8. The molecular weight of the enzyme was estimated to be 126,000, with two identical subunits. These results suggest that, in Chlorella, as in bovine liver mitochondria and Euglena, both 4,5-dioxovalerate and glyoxylate aminotransferase activities are associated with the same protein. From the activity ratio of transamination and catalytic properties, it is concluded that this enzyme does not function primarily as a part of the 5-carbon pathway to 5-aminolevulinic acid synthesis.

Catalysis↗
PubMed1984

Erythrocyte glutathione reductase activity and acquired trisomy #8 in various hematologic disorders.

The gene for erythrocyte glutathione reductase (E-GR) activity has been assigned to chromosome #8. In the present series, we examined the E-GR activity in 14 cases with chronic myelodysplastic syndrome (CMS, preleukemia), atypical acute myelogenous leukemia (AML), or chronic myelogenous leukemia (CML), with and without acquired trisomy #8. No difference in the incidence of high levels of this enzyme was found between two groups, i.e., those with and without trisomy #8 suggesting the existence of a complex regulatory system in addition to chromosome #8.

Chromosomes, Human, 6-12 and X↗
PubMed1984

A case of sicca syndrome due to primary amyloidosis.

We report the rare occurrence of sicca syndrome associated with primary amyloidosis. A 63-year-old man with apparent keratoconjunctivitis sicca and xerostomia died of the cardiac failure. Neither sialography nor labial gland biopsy revealed findings compatible with Sjögren's syndrome. Macroglobulinemia and a positive Bence-Jones protein were noted in urine testing. Amyloid deposition was demonstrated by Congo red staining on biopsied rectal tissues, and by typical birefringence under polarized light microscopy. At autopsy, the amyloid deposition was identified histochemically in the submandibular gland and the minor salivary glands of oral cavity.

Amyloidosis↗
PubMed1983

Complexes of immunoglobulins A and G with aspartate aminotransferase isoenzymes in serum.

We report the presence of complexes between aspartate aminotransferase (AST, EC 2.6.1.1) and immunoglobulin (Ig) in the serum of a patient suffering from lung cancer with metastasis to the liver. After fractionation of the serum by gel filtration, AST-Ig complexes (AST-IgA, AST-IgG) were demonstrated by counterimmunoelectrophoresis. Dissociating the complexes and recombining them with purified isoenzyme fractions, s-AST (cytoplasmic) and m-AST (mitochondrial), revealed that only s-AST binds to IgG, whereas IgA binds to both s-AST and m-AST. Although the association of AST with IgG has been reported, to our knowledge this is the first finding of both AST-IgA and AST-IgG complexes in a patient's serum. Serum AST-IgG complexes have been demonstrated in both healthy and diseased individuals; in the latter category, as reported here and by others, the liver is implicated.

Aged↗