THE DISTRIBUTION OF SOLUBLE AND MEMBRANE-BOUND FORMS OF GLUTAMINASE IN PIG BRAIN

Abstract— About 10% of the glutaminase activity associated with pig brain mitochondria was readily extractable by a variety of techniques but the remainder was very resistant to extraction. These two forms, which have been termed the soluble and membrane-bound forms respectively, have been shown to differ in their responses to activation by phosphate and phosphate-borate containing buffers. Submitochondrial fractionation studies indicated that the soluble form was located in the mitochondrial inner matrix whereas the membrane-bound form was associated with the inner membrane. The mitochondria associated with the synaptosomes were found to contain only the membrane-bound form of the enzyme whereas both forms were present in the free brain mitochondria.