P. Banfi et al., THE DAUNORUBICIN-BINDING PROTEIN OF M(R)-54,000 IS AN ALDEHYDE DEHYDROGENASE AND IS DOWN-REGULATED IN MOUSE-LIVER TUMORS AND IN TUMOR-CELL LINES, Molecular pharmacology, 46(5), 1994, pp. 896-900
A rabbit antiserum developed against purified rat liver daunorubicin-b
inding protein of M(r) 54,000 (DNR-BP54) cross-reacted with a mouse pr
otein of the same molecular weight. This protein was expressed in the
liver and several other organs of mice. A series of tumors and cell li
nes tested for the presence of the protein were negative. By immunocyt
ochemistry, we found that DNR-BP54 was abundantly expressed in the cyt
oplasm of normal hepatocytes but was expressed at much lower levels in
urethane-induced mouse liver tumors. By immunoscreening of a mouse li
ver cDNA library, we cloned the cDNA coding for DNR-BP54 and we found
that this protein is aldehyde dehydrogenase-2 (EC 1.2.1.3). This resul
t was confirmed by the dehydrogenase activity found in pure preparatio
ns of DNR-BP54 from normal rat and mouse livers, assayed with acetalde
hyde as substrate and NAD as cofactor. The enzyme activity was inhibit
ed by daunorubicin. The inhibition was found to be competitive with re
spect to NAD.