ALTERNATIVE SPLICING OF THE RABBIT BETA-GLOBIN PRE-MESSENGER-RNA IN-VIVO AFTER TRANSIENT TRANSFECTION OF MYOBLAST AND MYOTUBE CELLS

The relationship between preferences among alternative 5' splice sites and their sequences was investigated using as model mouse myoblasts a nd myotubes after transient transfection with the rabbit beta-globin g ene. The preferences for the use of two different 5' splice sites, act ing with different efficiencies to direct splicing in vivo are reporte d. The predominant selection of the upstream splice site has been show n in normal mouse myoblasts. In the case of differentiated myotubes th e downstream splice was 1.4 times better used. The results indicate th at there were differences in the preferences for the use of the two al ternative splice sites between non-differentiated and terminally diffe rentiated cells, within the same cell line.