QUANTITATIVE-DETERMINATIONS OF THE STEADY-STATE TRANSCRIPT LEVELS OF HEXOKINASE ISOZYMES AND GLUCOSE-TRANSPORTER ISOFORMS IN NORMAL RAT-TISSUES AND THE MALIGNANT-TUMOR CELL-LINE AH130

The steady state transcript levels of the four hexokinase (HK) isozyme s and four glucose transporter (GLUT) isoforms were determined quantit atively by Northern analysis of RNA samples from rat tissues using syn thetic fragments of the RNAs encoding the HK isozymes and GLUT isoform s. Results showed that the levels of HK isozyme transcripts were low i n rat tissues, the level of that most highly expressed, the type I iso zyme (HKI), in the brain being 0.025% of the total poly(A)(+) RNA. A g ood correlation was found between the reported HK activities and the t otal amounts of transcripts encoding all HK isozymes in various tissue s, showing that the HK activities in tissues can be estimated from the total amount of transcripts encoding HK isozymes. The proposed associ ated expressions of HK isozymes and GLUT isoforms in particular tissue s were confirmed at their transcript levels. The steady state transcri pt levels of type II HK and the type 1 GLUT isoform in the malignant t umor cell line AH130 were also determined quantitatively. (C) 1998 Els evier Science B.V.