Identification and topography of substrates for protein carboxyl methyltransferase in synaptic membrane and myelin-enriched fractions of bovine and rat brain.
J Neurochem
; 45(4): 1119-27, 1985 Oct.
Article
em En
| MEDLINE
| ID: mdl-4031881
ABSTRACT
The major components of crude brain synaptosomes (synaptic membranes, mitochondria, and myelin) have been separated and analyzed by polyacrylamide gel electrophoresis for the presence of proteins that serve as substrates for protein carboxyl methyltransferase. Of the three fractions, synaptic membranes contain the largest number of individual methyl acceptors (at least seven), while mitochondria contain no well-defined methyl acceptors. Undisrupted myelin contains a single major methyl acceptor with a very low apparent molecular weight. The patterns of protein methylation in synaptic membranes prepared from cerebral cortex, hippocampus, striatum, thalamus, and tectum showed marked differences; however, these differences could largely be explained by differential degrees of myelin contamination in synaptic membranes from the different regions. The effect of trypsin pretreatment on the carboxyl methylation of intact and lysed synaptosomes was studied to estimate the sidedness of the major methylation sites on synaptic membranes. One of the methyl acceptors (Mr 48K) appears to be facing the intracellular surface of the synaptosome, but most sites appear to be outward facing.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas Metiltransferases
/
Proteína O-Metiltransferase
/
Membranas Sinápticas
/
Encéfalo
/
Bainha de Mielina
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1985
Tipo de documento:
Article