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Distribution of Branch Point Prenyltransferases in Regions of Bovine Brain
Author(s) -
Runquist M.,
Parmryd I.,
Thelin A.,
Chojnacki T.,
Dallner G.
Publication year - 1995
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 - 10.1046/j.1471-4159.1995.65052299.x
Subject(s) - medulla oblongata , pons , farnesyl pyrophosphate , biochemistry , squalene , medulla , chemistry , biology , enzyme , biosynthesis , central nervous system , endocrinology , anatomy
Bovine brains contain large amounts of isoprenoid compounds and the enzymes involved in their biosynthesis were investigated. Ten different regions were dissected from fresh bovine brains and, in addition, fractions from cerebellum, spinal cord, and hypophysis were obtained. The cholesterol concentration was found to be ∼8 mg/g in the cortex regions and three times higher in the pons, medulla oblongata, and white matter. Dolichol concentration varied between 8 and 40 µg/g in the different tissues, and ubiquinone was found at a lower level, which varied between 3 and 25 µg/g. Farnesyl‐pyrophosphate synthase activity in cytosolic fractions from various regions exhibited only a twofold variation, whereas geranylgeranyl pyrophosphate synthase displayed larger differences, being particularly rich in the pons, medulla oblongata, white matter, and spinal cord. Squalene synthase activity was lowest in the thalamus and threefold higher in the pons. Determination of specific activity based on cholesterol content revealed that enzyme activities in various regions are not related to the actual lipid amount present. Both cis ‐ and trans ‐prenyltransferases exhibited similarities in their regional distribution showing up to 20‐fold differences in activity. Thus, it appears that the mevalonate pathway lipids and the various branch point enzymes involved in their syntheses vary greatly in different brain regions and are subjected to separate regulation.