CELLULAR-DISTRIBUTION OF 6-PHOSPHOFRUCTO-1-KINASE ISOENZYMES IN RAT-BRAIN

In the brain, all three isoenzyme types [muscle (M), liver (L), and br ain (C)] of 6-phosphofructo-1-kinase (PFK; EC 2.7.1.11) occur, forming a complex mixture of home- and heterotetramers. The PFK isoenzyme pat tern of the different brain cell types is yet unknown. In the present study, we investigated the distribution of the PFK isoenzyme subunits in primary and secondary cell cultures and in bulk-isolated cells of r at brain by means of sodium dodecyl sulfate-polyacrylamide gel electro phoresis and western blotting. All three PFK isoenzymes are present in all cell types but in different proportions. The cellular distributio n of the PFK isoenzymes in situ was studied immunohistochemically with different polyclonal antisera against purified rat PFKs. The monospec ific antibody against M-type PFK stained preferentially the perinuclea r areas of neurons and glial cells. The antibodies that in immunoblots detected mainly the L-type PFK showed a characteristic staining in on ly the cytoplasma and the processes of cells, whereas the C-type antib odies almost homogeneously stained whole cell bodies as well as large dendrites. Because the PFK isoenzymes differ with respect to their all osteric properties, their differential distribution in different brain cells might be of importance for the regulation of brain glycolysis i n the different cellular compartments of the brain.