Growth of liver accompanied by an increased binding of aminoacyl-transfer ribonucleic acids

Abstract

Homogenates of rat liver obtained 3 or 14 days after partial hepatectomy were used to prepare the postmicrosomal pH 5-supernatant fraction and to prepare saltwash fractions of the 40S ribosomal subunits and the 80S ribosomes. The factordependent binding of methionyl-tRNAfMet to ribosomes and the elongation-factor-ldependent binding of phenylalanyl-tRNA to ribosomes were both increased after 3 days of growth, but not after 14 days of growth. An activity inhibitory to phenylalanyl-tRNA binding that was located in ribosomal wash fractions was decreased after 14 days of growth. Since the decreased inhibitory activity was obtained from the ribosomes and was tested against ribosomes and excess of pH5-supernatant fraction from control rat liver, its action was separate from the phenylalanyl-tRNA binding activities of the pH 5-supernatant fractions from sham-operated and regenerating liver.

Studies on the Valyl-h-tRNA Synthetase of Chick Embryo Brain Irradiated with60Co γ-rays,in Vivo

“…There are three phases in the embryonic life of the chicken according to Romanoff (1967) . There are three phases in the embryonic life of the chicken according to Romanoff (1967) .…”

“…Furthermore, it is well known that a high rate of protein synthesis and, closely correlated to this, an increased activity of aminoacyl-tRNA synthetases occurs in rapidly growing tissues, e .g .. in regenerating liver (McEwen, Nicholls, Carey and Sendecki 1977) and in tumour tissues (Kushner, Boll, Quagliana and Dockman 1976) . Furthermore, it is well known that a high rate of protein synthesis and, closely correlated to this, an increased activity of aminoacyl-tRNA synthetases occurs in rapidly growing tissues, e .g .. in regenerating liver (McEwen, Nicholls, Carey and Sendecki 1977) and in tumour tissues (Kushner, Boll, Quagliana and Dockman 1976) .…”