The mouse beta h1 gene codes for the z chain of embryonic hemoglobin

Beta h0 and beta h1 are two beta-like globin genes in the mouse beta-globin gene cluster whose functions have not previously been established. Transcripts of both beta h0 and beta h1 are found in yolk sac-derived erythroid cells from mouse embryos and in the murine erythroleukemic cell line GM979. S1 nuclease analysis shows that beta h1 is the more abundant of the two transcripts in both embryonic erythroid cells and the cell line GM979. Hybridization of a beta h1-specific probe to RNA from erythroid cells of 10-, 11-, 12-, 13-, and 14-day-old mouse embryos indicates that levels of beta h1 mRNA are high at 10 and 11 days and then decline during further fetal development. The in vitro translation product of hybrid-selected beta h1 mRNA was analyzed by acid/urea polyacrylamide gel electrophoresis. The beta h1 translation product has the electrophoretic mobility expected for the z chain. We conclude that beta h1 is a fully functional gene which codes for the embryonic z chain.