. Biological structure and function; proceedings. Biochemistry; Cytology. NUCLEAR PROTEIN SYNTHESIS 265 protein particles of the nucleus. The association of the activating enzymes with particles which have been proven to be intranuclear (see below) is additional evidence for the conclusion that the nucleus itself carries out the amino acid activation reaction. AMINO ACID TRANSFER TO NUCLEAR RIBONUCLEIC ACID Studies of many cytoplasmic and bacterial systems have shown that the sequel to amino acid activation is a transfer reaction in which the 1500. RNA (00671^ chloramphenicol) Protein (0067 M
. Biological structure and function; proceedings. Biochemistry; Cytology. NUCLEAR PROTEIN SYNTHESIS 265 protein particles of the nucleus. The association of the activating enzymes with particles which have been proven to be intranuclear (see below) is additional evidence for the conclusion that the nucleus itself carries out the amino acid activation reaction. AMINO ACID TRANSFER TO NUCLEAR RIBONUCLEIC ACID Studies of many cytoplasmic and bacterial systems have shown that the sequel to amino acid activation is a transfer reaction in which the 1500. RNA (00671^ chloramphenicol) Protein (0067 M chloramphenicol) i —n 10 20 30 40 50 60 Time (min) Fig. 2. The time course of uptake of [i-^^C]-leucine into the protein and " carrier" RNA of isolated thymus nuclei. The specific activity of the total nuclear protein () is plotted in the upper curve. The incorporation into protein is greatly inhibited by the presence of chloramphenicol (lower curve). The uptake of amino acid into the RNA is the same in chloramphenicol-treated nuclei as in "controls". activated amino acid is coupled to a soluble ribonucleic acid, according to the equation: enzyme—amino acyl ~ AMP + sRNA^ amino acyl—sRNA +enzyme + AMP [24-28]. A similar process occurs in the isolated thymocyte nucleus [19, 29]. The transfer of amino acid to RNA in the nucleus can be shown directly by isolation of radioactive "carrier" RNA after incubating nuclei in the presence of a radioactive amino acid and chloramphenicol [19] or puromy- cin [29, 30]. The addition of either of these antibiotics blocks amino acid incorporation into nuclear protein, but does not interfere with the forma- tion of the amino acyl-RNA complex [29]. The RNA can then be prepared by the phenol method [31, 32] without risk of contamination by radio- active protein. The results of such an experiment are summarized in Fig. 2, in which the specific activities of nuclear protein and nuclear "phenol".
Size: 2008px × 1245px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiver, booksubjectbiochemistry
