TISSUE DISTRIBUTION OF HUMAN ALDEHYDE DEHYDROGENASE E3 (ALDH9) - COMPARISON OF ENZYME-ACTIVITY WITH E3 PROTEIN AND MESSENGER-RNA DISTRIBUTION

The tissue distribution of the E3 isozyme of human aldehyde dehydrogen ase has been investigated by three methods: enzyme activity assay empl oying betaine aldehyde as substrate, Western blotting employing E3 iso zyme-specific antibodies, and Northern blotting using a human liver E3 cDNA as probe. All three methods showed that E3 isozyme was universal ly distributed among all tissues tested. The highest levels of the E3 isozyme activity were found in liver, adrenal gland, and kidney. These same tissues also showed highest levels of the E3 protein via the Wes tern blot. This distribution is consistent with the possible physiolog ical role of E3 isozyme in the synthesis of the osmolyte, betaine, and the neurotransmitter, GABA. Northern blot analysis, however, differed from that of enzyme assay and the Western blot in that it showed high est mRNA levels in skeletal and heart muscles, which had low enzyme ac tivities and E3 protein levels. (C) 1997 Elsevier Science Inc.