Partial purification and characterization of the messenger RNA for human glucose-6-phosphate dehydrogenase

Glucose-6-phosphate dehydrogenase (G6PD) is a household enzyme that accounts, in many cells, for about 0.03% of cellular protein. We have developed an assay for G6PD-specific mRNA based on in vitro translation of RNA from human fibroblasts and immunoprecipitation of the translation products with an anti-G6PD antiserum. By making use of this assay, G6PD mRNA has been purified 50 to 100-fold in three steps. We estimate that the mRNA encoding G6PD constitutes less than 0.02% of total poly(A)+ RNA in human fibroblasts. The size of the G6PD mRNA has been established in denaturing conditions as being in the range between 2800 and 3200 nucleotides. This has been confirmed by Northern blot analysis. Since the G6PD coding sequence is estimated to be about 1491 nucleotides, the G6PD mRNA has long untranslated sequences, most of which is at the 3' end and which may be heterogeneous in length. The sequence of the last 608 nucleotides of this mRNA has been determined.