Mapping of a human genetic regulator element by somatic cell genetic analysis

The ES-2 esterase is a kidney-associated esterase and is expressed in a cloned mouse renal adenocarcinoma cell line. Somatic cell hybridization of the mouse renal adenocarcinoma with either mouse or human fibroblasts leads to the marked reduction of ES-2 esterase titer. The extinction of ES-2 esterase activity in mousexhuman hybrids is reversible. Extinction correlates with the presence of the human C(10) chromosome in the somatic cell hybrids; whereas reexpression of the ES-2 esterase is observed in hybrids which have lost C(10). Thus, the proposed regulator element involved is probably structurally linked to C(10); however, linkage to a member of the D or G groups cannot be completely excluded.