scholarly journals Construction, aminoacylation and 80 S ribosomal complex formation with a yeast initiator tRNA having an arginine CCU anticodon

FEBS Letters ◽  
1986 ◽  
Vol 202 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Nicole Beauchemin ◽  
Henri Grosjean ◽  
Robert Cedergren
Keyword(s):  
Complex Formation ◽  
Initiator Trna ◽  
Ribosomal Complex

scholarly journals Early effects of dimethylnitrosamine on the initiation of protein synthesis in mouse liver

1981 ◽  
Vol 194 (2) ◽  
pp. 469-474
Author(s):  
O Nygård ◽  
T Hultin
Keyword(s):  
Protein Synthesis ◽  
Complex Formation ◽  
Intraperitoneal Injection ◽  
Mouse Liver ◽  
Initiation Complex ◽  
Ribosomal Subunits ◽  
Single Intraperitoneal Injection ◽  
System 2 ◽  
Early Effects ◽  
Ribosomal Complex

1. Dimethylnitrosamine (37.5 mg/kg body wt.) was administered to mice by a single intraperitoneal injection, and the early effects on protein synthesis and related functions were studied in a liver S-30 system. 2. The incorporation of [14C]leucine into protein decreased rapidly after dimethylnitrosamine administration. The effect was associated with a decreased ability of the system to utilize methionyl-tRNAfMet and formyl-methionyl-tRNAfMet for 80 S ribosomal initiation-complex formation (primary initiation), and a loss of poly(A)-containing RNA from the postmicrosomal fraction. All the three effects developed simultaneously, and were clearly demonstrable within 15 min. 3. Initiation-complex formation in the polyribosomal fraction (re-initiation) was decreased to the same extent as the primary initiation, indicating that the initiation defect was not a result of the decrease in free mRNA. 4. The inhibition of initiation was only manifest at the joining of the 40 S pre-initiation complex to 60 S ribosomal subunits. It was not a result of methionyl-tRNAfMet deacylation. The functions between the formation of the methionyl-tRNAfMet-containing 80 S ribosomal complex and the first translocation on the ribosome were not involved, since the incorporation of formylmethionine into N-terminal polypeptides decreased to the same extent as the 80 S initiation-complex formation. 5. Inhibitors of protein synthesis (cycloheximide and pactamycin) decreased poly(A)-containing RNA in the postmicrosomal fraction in a similar way to dimethylnitrosamine.

scholarly journals Purification and some properties of a protein binding and deacylating initiator transfer ribonucleic acid

1979 ◽  
Vol 177 (2) ◽  
pp. 707-719 ◽  
Author(s):  
Petr Pohlreich ◽  
Oldřich Kříž ◽  
Zdena Tuháčková ◽  
Zdeněk Dušek ◽  
Jan Hradec
Keyword(s):  
Ternary Complex ◽  
Gradient Centrifugation ◽  
Ribosomal Subunit ◽  
Sucrose Density Gradient ◽  
Regulatory Function ◽  
Stable Complex ◽  
Sucrose Density Gradient Centrifugation ◽  
Initiator Trna ◽  
Protein Factor ◽  
Ribosomal Complex

1. A protein factor promoting the binding of initiator tRNA to the 40S ribosomal subunit was purified to homogeneity (more than 2500-fold) from rat liver cytosol. It has a mol.wt. of 265000 and is composed of four subunits of identical molecular weight. 2. This factor directs the binding of methionyl-tRNAfMet and to a lesser extent also of N-acetylphenylalanyl-tRNA, but not of methionyl-tRNAMet or phenylalanyl-tRNA, to the smaller ribosomal subunit at high concentrations of GTP (8–10mm) with an optimum at pH4.0. As evidenced by sucrose-density-gradient centrifugation, initiator tRNA becomes bound to the 40S subunit or to 80S ribosomes. 3. A deacylase activity specific for methionyl-tRNAfMet is associated with the pure factor. The factor significantly stimulates the translation of natural message in systems containing polyribosomes and both purified peptide-elongation factors. 4. The factor binds initiator tRNA or GTP to form unstable binary complexes and forms a ternary complex with methionyl-tRNAfMet and GTP. This complex is relatively stable. 5. In the absence of any cofactors the factor forms a stable complex with 40S and 80S ribosomes. This preformed ribosomal complex binds efficiently initiator tRNA at pH7.5 and low concentrations of GTP (1–2mm). The ternary complex of the factor with methionyl-tRNAfMet and GTP may be liberated from this ribosomal complex. 6. A protein factor capable of promoting the binding and simultaneously the deacylation of initiator tRNA may apparently have a regulatory function in physiological gene translation by removing an excess of methionyl-tRNAfMet not required for translation.

Initiator-tRNA recognizes a tetranucleotide codon during the 30 S initiation complex formation

FEBS Letters ◽  
1978 ◽  
Vol 90 (1) ◽  
pp. 162-166 ◽  
Author(s):  
Ulrike Manderschied ◽  
Sabine Bertram ◽  
Hans Günter Gassen
Keyword(s):  
Complex Formation ◽  
Initiation Complex ◽  
Initiator Trna

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Inactivation of α- and β-Thrombin by Antithrombin-III and Heparin

1976 ◽  
Vol 36 (03) ◽  
pp. 503-508 ◽  
Author(s):  
Raymund Machovich ◽  
György Blaskó ◽  
Anna Borsodi
Keyword(s):  
Heat Treatment ◽  
Complex Formation ◽  
Blood Circulation ◽  
Antithrombin Iii

SummaryInactivation of α- and β-thrombin by antithrombin-III and heparin was studied, since it had been suggested that two forms of thrombin exist with respect to heparin sensitivity (Machovich 1975b).It was found that the inactivation rates of α- and β-thrombin by antithrombin were different, namely α-thrombin was more sensitive to antithrombin than β-thrombin. Heparin facilitated the complex formation between α-thrombin and antithrombin-III, whereas β-thrombin inactivation was only slightly affected.Furthermore, heparin protected α-thrombin against the inactivating effect of heat, while β-thrombin lost its activity during the heat treatment.These findings suggest that the formation of β-thrombin in blood circulation may have an important role in thrombosis predisposition.

Factor VIII Inhibitor Antibodies with C2 Domain Specificity Are Less inhibitory to Factor VIII Complexed with von Willebrand Factor

1996 ◽  
Vol 76 (05) ◽  
pp. 749-754 ◽  
Author(s):  
Suzuki Suzuki ◽  
Morio Arai ◽  
Kagehiro Amano ◽  
Kazuhiko Kagawa ◽  
Katsuyuki Fukutake
Keyword(s):  
Complex Formation ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Domain Specificity ◽  
Factor Viii Inhibitor ◽  
C2 Domain ◽  
Recombinant Fviii ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

SummaryIn order to clarify the potential role of von Willebrand factor (vWf) in attenuating the inactivation of factor VIII (fVIII) by those antibodies with C2 domain specificity, we investigated a panel of 14 human antibodies to fVIII. Immunoblotting analysis localized light chain (C2 domain) epitopes for four cases, heavy chain (A2 domain) epitopes in five cases, while the remaining five cases were both light and heavy chains. The inhibitor titer was considerably higher for Kogenate, a recombinant fVIII concentrate, than for Haemate P, a fVIII/vWf complex concentrate, in all inhibitor plasmas that had C2 domain specificity. In five inhibitor plasmas with A2 domain specificity and in five with both A2 and C2 domain specificities, Kogenate gave titers similar to or lower than those with Haemate P. The inhibitory effect of IgG of each inhibitor plasma was then compared with recombinant fVIII and its complex with vWf. When compared to the other 10 inhibitor IgGs, IgG concentration, which inhibited 50% of fVIII activity (IC50), was remarkably higher for the fVIII/vWf complex than for fVIII in all the inhibitor IgGs that had C2 domain reactivity. Competition of inhibitor IgG and vWf for fVIII binding was observed in an ELISA system. In 10 inhibitors that had C2 domain reactivity, the dose dependent inhibition of fVIII-vWf complex formation was observed, while, in the group of inhibitors with A2 domain specificity, there was no inhibition of the complex formation except one case. We conclude that a subset of fVIII inhibitors, those that bind to C2 domain determinants, are less inhibitory to fVIII when it is complexed with vWf that binds to overlapping region in the C2 domain.

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