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In Vitro Synthesis of Human Brain Proteins Including Tubulin and Actin by Purified Postmortem Polysomes
Author(s) -
Marotta Charles A.,
Brown Beverly A.,
Strocchi Paola,
Bird Edward D.,
Gilbert Jeffrey M.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb01688.x
Subject(s) - polysome , tubulin , in vitro , actin , biology , microbiology and biotechnology , biochemistry , microtubule , rna , ribosome , gene
Polysomes were prepared from human brain tissue 2‐6 h postmortem; the polysomes were active in a cell‐free protein synthesis system containing rabbit reticulocyte factors. Protein synthesis was totally dependent upon added MgCl 2 , ATP, the reticulocyte factor fraction, and the human polysome fraction. Human brain proteins synthesized in the presence of L‐[ 35 S]methionine were analyzed by one‐ and two‐dimensional polyacrylamide gel electrophoresis. Over 250 proteins were synthesized and they extended in size up to 250,000 d; many of the most abundant native human brain proteins were synthesized, including tubulin and actin. It was shown that human brain α and β tubulin and actin isomers synthesized in vitro from human postmortem polysomes have the same apparent molecular weights and isoelectric points as the corresponding proteins synthesized by rat polysomes from fresh cortices. The corresponding tubulin and actin synthesized by human and rat brain polysomes also yield the same radioactive methionine‐containing peptides after digestion with Staphylococcus aureus V8 protease. These analyses indicate that postmortem polysomes contain active messenger RNA which can direct the partial and/or complete synthesis of actin and tubulin subunits and other human brain proteins.