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Studies on the Cell‐Free Biosynthesis of CNS Membrane Proteins
Author(s) -
Gilbert Jeffrey M.,
Strocchi Paola
Publication year - 1983
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.1471-4159.1983.tb12665.x
Subject(s) - polysome , endoplasmic reticulum , biology , membrane protein , cytoplasm , cytosol , biochemistry , membrane , cell fractionation , cell free system , protein biosynthesis , concanavalin a , cell membrane , population , microbiology and biotechnology , ribosome , rna , gene , in vitro , enzyme , demography , sociology
The biosynthesis of CNS membrane proteins was studied in cell‐free systems containing membrane‐bound polysomes (rough endoplasmic reticulum; RER) or free polysomes from rat forebrain. In previous studies of CNS membrane proteins using two‐dimensional gel electrophoretic analysis, five proteins (mol. wt.‐pI: 75K 5.4, 68K 5.6, 61K 5.1, 58K 5.1, and 36K 5.6) were found in ceil membrane fractions including preparations enriched in RER, smooth endoplasmic reticulum, and plasma membranes. One of these proteins, 68K 5.6, was also present in cytosol and comigrated with a microtubule‐associated protein. In our present study, cell‐free systems containing RER were found to synthesize the 75K 5.4, 61K 5.1, and 58K 5.1 proteins. A protein, 34K 5.65, similar (but not identical) to the 36K 5.6 protein was also synthesized. After cell‐free synthesis, the 75K 5.4 and 58K 5.1 proteins could be purified by concanavalin A affinity chromatography. Of the five common membrane proteins previously identified, only the 68K 5.6 protein was synthesized by the free polysome population. The free polysomes were also found to synthesize cyclic AMP binding proteins at 48K and 54K, known from previous studies to be present in both cytosol and plasma membrane fractions in mammalian brain tissue. In conclusion, RER synthesized proteins found exclusively in CNS membrane fractions, whereas free polysomes synthesized those proteins found in both soluble and membrane compartments.