Embryonal carcinoma cells defective in the expression of developmentally regulated
carbohydrate epitope of
teratocarcinoma cells (TEC-1) were isolated from mutagenized P19X1 and P19S1801A1 cells by a single-step selection technique using
monoclonal antibody TEC-01 conjugated to plant
toxin ricin. Three independently isolated mutant cell lines were characterized in detail. Analysis of the expression of the TEC-1
epitope in somatic cell hybrids constructed between wild-type and mutant cells and between two mutant cell types revealed that the mutant phenotypes are recessive and that the mutants belong to, at least, two complementation groups. Each mutant cell line exhibited a unique binding pattern of four
monoclonal antibodies and five
lectins, and different properties of large
glycopeptides were distinguished by
Sephadex G-50 column chromatography. The combined data suggest that our mutants identify three genes involved in the synthesis of
embryoglycan, one of which appears to be the regulatory or structural gene for
fucosyltransferase. One mutant cell line was completely deprived of
embryoglycan and several
carbohydrate structures typical of early embryonic and embryonal carcinoma cells; however, the cells were similar to parental cells in their morphology, their ability to form aggregates when cultured in
suspension, their ability to differentiate into neuron-like cells
after treatment with
retinoic acid, and their ability to form
tumors composed of embryonal carcinoma cells. Thus,
embryoglycan is not required for the expression of a number of properties of the
embryonal carcinoma phenotype.