Structure and expression of the mouse beta 2-microglobulin gene isolated from somatic and non-expressing teratocarcinoma cells.

Mouse teratocarcinoma cells express neither H-2 heavy chains nor beta 2-microglobulin (beta 2-m). We have constructed two genomic libraries, one from PCC4-aza-RI embryonal carcinoma cells and the other from their adult syngenic counterpart 129/Sv liver cells (H-2bc). The libraries were screened with a full length mouse beta 2-m cDNA probe which we isolated and sequenced. Two cosmid clones carrying the entire beta 2-m gene were isolated, one from each library. There was no detectable difference in structure between the two genes. Furthermore, both were shown to be active and to restore beta 2-m synthesis upon transfer into mutant cells deficient in beta 2-m. Irreversible DNA alterations in or around the beta 2-m gene are thus unlikely to account for the lack of beta 2-m gene expression in embryonal teratocarcinoma cells.