Comparison of cell-free protein synthesis by different regions of chicken brain

Abstract

The cell-free protein synthesis by the postmitochondrial supernatant from chicken cerebrum was twofold greater than protein synthesis by the cerebellum or optic lobes. Ribosomal aggregation of mRNA and ribonuclease activity of the postmitochondrial supernatant from the three brain regions was not statistically different. The higher protein synthetic activity of the cerebral postmitochondrial supernatant was associated with both the postribosomal supernatant (cell sap) and microsomal fractions. Cerebral monomeric ribosomes were more active in polyuridylic acid directed polyphenylalanine synthesis than monomeric ribosomes from either the cerebellum or optic lobes. The ability of cerebral cell sap to support polyuridylic acid directed polyphenylalanine synthesis was 1.6 to 2 times greater than cell sap from the other two regions. Cell sap factors other than tRNAphe or phenylalanyl-tRNA synthetases appear to be responsible for the higher protein synthetic activity of the cbr cell sap.

Biphasic Modulation by ACTH‐Like Peptides of Protein Synthesis in a Cell‐Free System from Rat Brain

“…In brain, changes in the in vivo rates of protein synthesis can be reflected by differences in the activity of a postmitochondrial supernatant for cell-free protein synthesis. This phenomenon was, e.g., observed for the effect of amphetamine (Widelitz et al, 1976), for differences between brain areas (Liu et al, 1978), for changes during development (Gilbert, 1978), and for differences as a result of levels of hormones and neuropeptides (Schotman et al, 1972(Schotman et al, , 1980.…”

Changes in Brain Protein Synthesis during the Life Span of Male Fischer Rats

“…Brain PMS from either young-adult or old rats had detectable ribonuclease activity. However, to our surprise, the ribonuclease activity of brain PMS from the old rats was consistently lower than that observed for the young-adult Ribonucléase activity of brain PMS was determined as described by Liu et al (19). Brain PMS prepared from young-adult (6-month-old) and old (28-month-old) rats were incubated at 37 °C in the homogenization buffer with (3H)-polyuridylic acid for 10 or 20 min.…”

“…The precipi tate was dried and dissolved in 0.3 N NaOH. The radioactivity in the NaOH solutions was determined using a liquid scintillation counter and the RNA concentration in the samples was determined as de scribed previously (18,19). We have shown previously that radioactively labeled ¿-valine is not metabolized to other amino acids when incubated with brain PMS at 37 °C for 60 min (19).…”

“…Polyuridylic acid-directed polyphenylalanine syn thesis was determined using ribosomes stripped of mRNA as described previously (19). Ribosomes were stripped of mRNA by incubating the PMS as 37 °C for 90 min with 0.1 mAf puromycin in the PMS cell-free protein synthesis system.…”

“…The remaining homog enate was centrifuged at 20,000 g for 10 min at 4 °C. The resulting supernatant, the postmitochondrial supernatant (PMS), was used for cell-free protein synthesis after Sephadex G-25 chromatography as described previously (18,19).…”