Esterase-30 (ES-30) of the house mouse: Biochemical characterization and genetics of a new carboxylesterase isozyme linked to cluster-2 loci on chromosome 8

A new carboxylesterase isozyme (EC 3.1.1.1), designated ES-30, is described in mouse liver. Two phenotypes were distinguished, ES-30A, a possible null type, was found in SPE/Pas and in other lines derived fromMus spretus, and ES-30B was found in BALB/cJ and other laboratory inbred strains. ES-30B is characterized by a distinct electrophoretic band when stained using 5-bromoindoxyl acetate as the substrate. After isolation and purification from other esterases by ion-exchange chromatography and molecular sieving, the molecular mass was estimated by two independent methods to be 62 and 64 kDa, respectively. The activity of ES-30B is higher in adult males than in females and can be stimulatedin vivo by testosterone. The distribution of phenotypes on the progeny of a backcross series suggests a separate locus,Es-30, with the allele a for absence andb for presence of the isozyme. LocusEs-30 is shown to be closely linked toEs-2 and toEs-7 of cluster-2 on chromosome 8. The gene orderEs-9—Got-2—(Es-2, Es-7, Es-30) is suggested. This work was supported by the Deutsche Forschungsgemeinschaft. This is communication No. 72 of a research program devoted to the cellular distribution, genetics, and regulation of nonspecific esterases.