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The number and classes of genes responsible for the final expression of lysosomal acid phosphatase were investigated in the mouse (Mus musculus). In mouse tissues, lysosomal acid phosphatase activity was separated by gel electrophoresis into two major zones of activity. The cathodal zone of activity in liver of the SM/J inbred strain was almost completely absent, while the anodal zone was increased in activity. Other tissues from SM/J were not affected, nor were livers and other tissues in 27 inbred mouse strains. Genetic studies indicated that this deficiency variant segregated as an autosomal codominant gene which has been designated Apl to symbolize the acid phosphatase liver phenotype. The Apl gene was not linked to markers on chromosomes 1, 2, 4, 5, 7, 8, or X. Electrophoretic, heat denaturation, neuraminidase treatment, tartrate inhibition studies and tissue mixing experiments suggested that the Aplgene was not a structural gene for acid phosphatase, but a separate gene that functions in liver and is responsible for controlling or modifying an acid phosphatase structural gene product.

Avian erythroblastosis virus, a retrovirus that causes erythroblastosis and sarcomas in infected birds, possesses two host cell-derived genes [viral (v) erb-A and erb-B]. Although v-erb-B seems to be responsible for oncogenic transformation, v-erb-A might have an enhancing effect on transformation. In chickens, the natural host for avian erythroblastosis virus, cellular (c) erb-A and erb-B genes appear to be unlinked, but their chromosomal locations in other species are unknown. To ascertain the chromosomal location of c-erb genes in man and mouse, we analyzed interspecies somatic cell and microcell hybrids by Southern filter hybridization techniques using specific v-erb-A and v-erb-B probes. We found c-erb-A sequences on human chromosome 17 (17p11----qter) and located c-erb-B on human chromosome 7 (7pter----q22). In contrast, both c-erb-A and c-erb-B reside on mouse chromosome 11.