title: Regulation of prenatal and postnatal protein synthesis in mouse brain.
abstract: Regulation of protein synthesis during prenatal and postnatal brain development was examined using postmitochondrial supernatant (PMS) fractions and isolated ribosome-pH 5 enzyme systems from fetal, neonatal, and adult neural tissue. The rate of polyuridylic acid (poly-U)-dependent protein synthetic activity was inversely proportional to the endogenous rate of protein synthesis in either the PMS fractions or ribosomal preparations. A careful analysis of the kinetics of the poly-U-dependent polypeptide synthesis revealed that there was a lag in the time at which certain of the PMS preparations could begin to utilize the poly-U template as sole source of mRNA. The lag period was dependent upon the developmental age of the neural tissue used and the Mg2+ concentration of the protein synthesis reaction. Since previous work reported that the observed developmental decrease in the rate of polypeptide synthesis utilizing a poly-U template could not be measured by several isolation techniques to determine if the purification procedure might have affected the ribosomes in some manner by removing a specific protein(s) involved in ribosome-cytosol interactions. At 6 mM-Mg2+ the rate of poly-U-dependent protein synthesis was inversely proportional to the rate of endogenous synthesis and depended upon the method used to isolate the ribosomes: microsomes congruent to Triton X-100-treated < DOC-treated < KCl-treated. However, there was no age-dependent effect with any of the ribosomal preparations. The data suggest that there is a developmental modulating effect of ribosomal activity in PMS preparations which is not found in association with the isolated ribosome-pH 5 enzyme protein synthesizing system.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D005333:Fetus; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D011072:Poly U; D011247:Pregnancy; D014176:Protein Biosynthesis; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D009419:Nerve Tissue Proteins; D011072:Poly U; D008274:Magnesium