scholarly journals Intermediate reactions in the binding of aminoacyl-transfer ribonucleic acid to rat liver ribosomes. The role of guanosine triphosphate

1972 ◽  
Vol 126 (4) ◽  
pp. 933-943 ◽  
Author(s):  
J. Hradec
Keyword(s):  
Rat Liver ◽  
Ternary Complex ◽  
Cellulose Nitrate ◽  
Stable Complex ◽  
Bacterial Cells ◽  
Guanosine Triphosphate ◽  
Binding Reaction ◽  
Aminoacyl Transfer ◽  
Liver Ribosomes

1. Transferase I from rat liver binds relatively low quantities of GTP when incubated with this nucleotide in the absence of aminoacyl-tRNA. 2. Transferase I reacts with both aminoacyl-tRNA and GTP to form a relatively stable complex that is retained on cellulose nitrate filters. The ternary complex transferase I–aminoacyl-tRNA–GTP is also formed when the transferase I–aminoacyl-tRNA complex is incubated with GTP or during the incubation of the transferase I–GTP complex with aminoacyl-tRNA. Synthesis of this complex does not require the presence of Mg2+. 3. In the presence of Mg2+ the ternary complex becomes readily bound to ribosomes without requirements for any other cofactors. 4. An extensive cleavage of GTP takes place when aminoacyl-tRNA becomes bound to ribosomes. 5. The low interdependence of reactions leading to the formation of transferase I complexes with aminoacyl-tRNA and GTP indicates that the mechanisms of the binding reaction in mammalian systems may be different from those in bacterial cells.

scholarly journals Intermediate reactions in the binding of aminoacyl-transfer ribonucleic acid to rat liver ribosomes. Formation and properties of an aminoacyl-transfer ribonucleic acid–transferase I complex

1972 ◽  
Vol 126 (4) ◽  
pp. 923-931 ◽  
Author(s):  
J. Hradec
Keyword(s):  
Ion Exchange ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Cellulose Nitrate ◽  
Stable Complex ◽  
Primary Reaction ◽  
Preparative Isolation ◽  
Reaction Proceeds ◽  
Aminoacyl Transfer ◽  
Liver Ribosomes

1. Transferase I of rat liver binds aminoacyl-tRNA to form a relatively stable complex, which is retained on cellulose nitrate filters. This reaction proceeds at both 0°C and 37°C and is inhibited by GTP. The resulting product is stabilized by GTP and Mg2+. 2. Only very low quantities of deacylated tRNA are bound by transferase I. 3. Methods are described for the preparative isolation of the transferase I–aminoacyl-tRNA complex from incubation mixtures by using ion-exchange procedures. 4. The transferase I–aminoacyl-tRNA complex becomes readily bound to ribosomes. The presence of Mg2+ is essential for the binding. GTP stimulates this reaction but is not absolutely required. 5. It is concluded that the formation of the transferase I–aminoacyl-tRNA complex may be the primary reaction in the binding of aminoacyl-tRNA to mammalian ribosomes and that, unlike in bacterial systems, GTP is not absolutely required for this step.

scholarly journals The Role of Guanosine Triphosphate Hydrolysis in Elongation Factor Tu-promoted Binding of Aminoacyl Transfer Ribonucleic Acid to Ribosomes

1973 ◽  
Vol 248 (1) ◽  
pp. 375-377 ◽  
Author(s):  
Hideyoshi Yokosawa ◽  
Noriko Inoue-Yokosawa ◽  
Ken-Ichi Arai ◽  
Masao Kawakita ◽  
Yoshito Kaziro
Keyword(s):  
Ribonucleic Acid ◽  
Elongation Factor ◽  
Elongation Factor Tu ◽  
Guanosine Triphosphate ◽  
Aminoacyl Transfer

scholarly journals The mechanism of guanosine triphosphate depletion in the liver after a fructose load. The role of fructokinase

1985 ◽  
Vol 228 (3) ◽  
pp. 667-671 ◽  
Author(s):  
M I Phillips ◽  
D R Davies
Keyword(s):  
Rat Liver ◽  
Intravenous Administration ◽  
Liver Homogenate ◽  
Guanosine Triphosphate ◽  
Phosphate Donor ◽  
Single Enzyme

A Sephadex G-25 filtrate of a 100 000g supernatant of rat liver homogenate was shown to be able to phosphorylate fructose, with GTP as the phosphate donor. Attempts to separate ATP- and GTP-dependent fructokinase activities failed, indicating that there is a single enzyme able to use both nucleotides. With a partially purified enzyme, Km values for fructose of 0.83 and 0.56 mM were found with ATP and GTP as substrates respectively. Km values of 1.53 and 1.43 mM were found for GTP and ATP respectively. Both ADP and GDP inhibited the GTP- and ATP-dependent fructokinase activity. We conclude that the depletion of hepatic GTP caused by intravenous administration of fructose to mice and rats can be explained simply by the utilization of the nucleotide by fructokinase.

scholarly journals Intermediate reactions in the binding of aminoacyl-transfer ribonucleic acid to rat liver ribosomes. The interaction of cholesteryl 14-methylhexadecanoate

1972 ◽  
Vol 126 (5) ◽  
pp. 1225-1229 ◽  
Author(s):  
J. Hradec
Keyword(s):  
Binding Site ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Binding Capacity ◽  
Original Activity ◽  
Aminoacyl Transfer ◽  
Liver Ribosomes

1. Transferase I from rat liver extracted with iso-octane binds significantly less aminoacyl-tRNA than the non-extracted enzyme. The original activity can be fully restored by the addition of cholesteryl 14-methylhexadecanoate. The binding capacity for GTP is not affected by the extraction. 2. In the presence of extracted transferase I the binding of aminoacyl-tRNA to ribosomes is decreased to 11–26% and the simultaneous binding of GTP to 32–43%. Cholesteryl 14-methylhexadecanoate induces a full reactivation of the extracted enzyme in both respects. 3. Extracted complexes A (aminoacyl-tRNA–GTP–transferase I) become bound to ribosomes to the same extent as the corresponding non-extracted preparations. 4. It is concluded that cholesteryl 14-methylhexadecanoate interacts with the binding site of transferase I for aminoacyl-tRNA and secondarily with that for GTP. It does not affect the binding site for ribosomes.

scholarly journals Binding of Purified Antialbumin by Rat Liver Ribosomes

1965 ◽  
Vol 240 (7) ◽  
pp. 3009-3015 ◽  
Author(s):  
William A. Warren ◽  
Theodore Peters
Keyword(s):  
Rat Liver ◽  
Liver Ribosomes
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