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Comparison of Protein Synthesis in Mitochondria, Synaptosomes, and Intact Brain Cells
Author(s) -
Irwin Carol C.
Publication year - 1985
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.1471-4159.1985.tb05433.x
Subject(s) - cycloheximide , mitochondrion , protein biosynthesis , percoll , biology , biochemistry , organelle , incubation , chloramphenicol , methionine , synaptosome , ficoll , microbiology and biotechnology , in vitro , amino acid , peripheral blood mononuclear cell , antibiotics
Qualitative aspects of protein synthesis in organelles and intact cultured cells of brain origin were compared to clarify the distinction between synaptosomal and mitochondrial protein synthesis. Brain mitochondria and synaptosomes were isolated either on a traditional Ficoll‐sucrose gradient or by a new Percoll gradient procedure, and were incubated in an amino acid incorporation system containing [ 35 S]methionine, then electrophoresed on gradient slab gels. Autoradiography of the gels revealed that in the presence of cycloheximide both mitochondria and synaptosomes synthesized at least 17 proteins in the 6,000‐50,000 MW range, and that incubation with chloramphenicol reduced or eliminated these bands. With minor variation these patterns in the low‐molecularweight region also resembled patterns obtained from cycloheximide‐inhibited rat liver mitochondria and intact brain cells (cultured glia, glioma, and neuroblastoma). In the higher molecular weight region of the gels (>50,000) banding patterns were more complex and tended to differ between organelles and intact cells. These polypeptides probably reflect nonmitochondrial protein synthesis, and their variable response to inhibitors may account for confusion in the literature with regard to the effects of inhibitors of protein synthesis in brain mitochondria and synaptosomes.