DIFFERENTIAL EXPRESSION OF A CONSERVED NEW MESSENGER-RNA IN LYMPHOID-CELLS

We describe a polyadenylated RNA (Drld = Differentially regulated in l ymphoid organs and differentiation) from murine lymphocytes. Two homol ogous molecular forms of this RNA of approximately 500 and 900 bases a re detected in various tissues and lymphoid cell lines. Southern blott ing showed that up to ten highly homologous loci exist which in part a re polymorphic between the different mouse strains analyzed. Cross-hyb ridizing loci can be detected in distantly related species such as hor se, fish and Drosophila melanogaster. Sequence analysis revealed homol ogies to the untranslated region of the GPI-linked murine B7(2) antige n, the B2 repetitive elements and 3 untranslated genes. Drld apparentl y defines a new family of genetic elements.