JBC, Vol. 252, Issue 5, 1819-1825, Mar, 1977
Synthesis of tubulin and actin by neuronal and glial nuclear preparations from devloping rat brain
I. Gozes, M. D. Walker, A. M. Kaye and U. Z. Littauer
A system was established in which nuclear preparations from rat brains were
capable of protein synthesis under cell-free conditions. The
electrophoretic pattern of the synthesized proteins was similar to that
found in vivo provided that the reaction mixture contained pH 5
precipitated factors derived from the high speed supernatant fraction of
brain. In the absence of the pH 5 factors, using nuclear preparations from
brains of 2-day-old rats, approximately 1.5% and 2% of the newly
synthesized proteins were identified as tubulin and actin, respectively. In
the presence of pH 5 factors, protein synthesis was stimulated and the
proportion of the newly synthesized tubulin and actin increased to 26% and
11%, respectively. In contrast to nuclear fractions from 2-day-old rats,
when nuclei from brains of 1-month-old rats were tested in the presence of
pH 5 factors, the proportion of tubulin and actin synthesized was lower and
amounted to 10% and 4%, respectively. The age-dependent change in the
relative amount of the tubulin and actin synthesized is in good agreement
with the translational pattern shown by brain polyribosomes in a brain
cell-free system as well as with the pattern obtained with brain mRNA
translated in a wheat germ cell-free system. Nuclei enriched for either
neuronal or glial populations synthesized similar proportions of tubulin
and actin in vitro. We conclude that the reduction in the synthesis of
tubulin and actin during the postnatal development of the rat brain occurs
in both neuronal and glial cells.