Relationships among DNA sequences of the 1.3 kb EcoRI family of mouse DNA.

The genome of the mouse (Mus musculus) contains a family of repeated DNA sequences defined by a 1.3 kb EcoRI fragment. Restriction maps of ten cloned fragments from this family have been determined. The fragments were of seven different types, based on the patterns of digestion obtained with AvaII, HindIII, and TaqI restriction enzymes. These seven unique sets of sequences fell into two classes, as defined by the position of a single HindIII site. Portions of fragments from each of the two classes were sequenced. Although certain regions of the repeat were highly conserved between classes, there was more intraspecific sequence divergence among the sequenced regions than has been observed for the short interspersed Alu family of repeated sequences in mammals. Sequences of both HindIII classes were found to be present within the mouse X chromosome; we can conclude that both classes must also be present on other mouse chromosomes.