Organ specific expression of esterase-6 in the house mouse, Mus musculus

Abstract

Esterase-6 in fresh homogenates of heart muscle and testis of the house mouse shows a two band (C allele) or three band (A allele) pattern in disc electrophoresis. These primary bands generated in series of secondary bands upon lowering the pH of the homogenates, and the secondary pattern, possibly resulting from partial proteolysis, was seen in varying degrees in fresh homogenates from a range of organs. Interrelationships between the primary and secondary bands were demonstrated by isoelectric focusing. The esterase-6 content of twenty different organ homogenates was estimated from electrophoretic gels, and a high level of this enzyme was observed in those organs most actively involved in fat metabolism. The possible participation of esterase-6 in fatty acid utilization is discussed. Similarities between esterase-6 of the house mouse and esterase-4 of the rat were demonstrated, further strengthening the view that these enzymes are homologous.

Purification and Characterization of Esterase 6A, a Trimeric Esterase of the House Mouse (Mus musculus)

“…As reported earlier, lowering the pH or organ homogcnatcs from 7.3 to 5.0 generates up to eight secondary bands of esterase 6A [7]. Purified esterase 6A, on thc other hand.…”

“…The molecular weight of 40000 obtained for 6A' on polyacrylamide gel electrophoresis is probably erroneously low (see below), indicating an interaction between the esterase and the gel. This apparently high hydrophobicity of esterase 6A is interesting in view of its presence in high concentrations in tissues actively involved in lipid metabolism, and possibly at the periphery of lipid droplets [7], and correlates with a proposed function in intracellular fat metabolism.…”

“…A confusing feature has been the occurrence of a variable, organ-dependent number of electrophoretically distinct bands, all associated with the same genetic locus. This has led to the designation of 'primary' and 'secondary' bands of esterase 6 [7].…”

“…The clear genetic definition of mouse esterases, however, makes them best suited to biochemical study. Esterase 6 is also of special interest in view of its possible participation in intracellular fatty acid utilization [7]. The biological function of most other non-specific esterases remains obscure.…”

“…This study presents the first isolation and biochemical characterization of esterase 6. Although it shows wide organ distribution, lung was chosen as the most suitable source of the isozyme, in view of the high proportion of esterase 6 in relation to other esterases and the absence of most secondary bands from lung homogenates [7]. The properties of esterase 6A reported here are compared with those of esterase 9A and esterase 1 F, with which esterase 6A is genetically closely linked.…”