A B1 repetitive sequence near the mouse beta-major globin gene.

A sequence which lies 2.8 kb to the 3' side of the BALB/c mouse beta-major globin gene has been identified by its ability to hybridise to a member of the human Alu repetitive sequence family. Nucleotide sequencing revealed a 133-bp region that shows 89% homology to the consensus sequence of the B1 family, the murine equivalent of the Alu family. To the 3' side of this sequence is a 31-bp region, C(A)3(C)2T(C)3G(C)11(A)9, which contains oligo(C) and oligo(A) tracts. The whole 164-bp sequence is flanked by a 16-bp imperfect direct repeat, G(A)4GGAGTCTCATAG. The orientation of the B1 sequence is such that transcription by RNA polymerase III would be expected to occur in the same direction as transcription of the neighbouring beta-major globin gene by RNA polymerase II.