Independent expression of alpha-HCG and placental alkaline phosphatase in clonal human cell lines.

The expression of the placental isoenzyme of alkaline phosphatase and the alpha subunit of chorionic gonadotropin was examined in a series of cloned lines of Chang liver cells. both placental gene products show large quantitative variation in the amounts made (over 30-fold) among the various clones. This variation occurs independently for both proteins. These results suggest that these placental-specific genes are discordantly regulated. Because karyologic analysis of several clones shows significant variation in the chromosome content, we cannot determine whether such expression results from true independent mechanisms controlling expression or from variation in gene dosage.