A novel 0.6 kb LINE family in human DNA, designated L2Hs, has been described (Musich and Dykes 1986). Studies employing clone N6.4, containing three 0.6 kb segments of this family, indicate that these sequences are interspersed and moderately repetitive. Two additional variant sequences of the L2Hs family, N6.1 and N6.3, have been identified. Restriction mapping of each cloned segment indicates similarities among N6.4, N6.3 and N6.1. When the cloned DNAs were cleaved with restriction enzymes and subjected to cross-hybridization, each cloned insert produced a pattern indicating that the sequences contained in N6.1 and N6.3 are represented in at least one of the three 0.6 kb segments within the clone N6.4. Hybridization of human genomic DNA digested with KpnI or KpnI+AccI reveals differences in nuclear organization for these segments. For any particular human DNA, the hybridization patterns for each of the three probes overlap. However, these differences indicate that the inserts in N6.1 and N6.3 and one of the N6.4 inserts each represents a subset of the L2Hs LINE family. Sequence analysis of N6.1 indicates that the probability of a functional translation product from N6.1 transcript is not high. The sequence contains stop and nonsense codons in all reading frames. However, the DNA has properties suggesting a structural, non-coding role. The N6.1 sequence contains 11 regions of alternating purine and pyrimidines which can affect the three dimensional structure and, therefore, the structural behavior of the molecule. In addition, putative binding regions for microtubule-associated proteins have been identified. A cloned variant of the XbaI family of repetitive DNAs, PuHu7, was identified. Studies of its genomic organization showed a tandem arrangement similar to other, previously described members of this family. The genomic organization of a previously undescribed repetitive DNA family is also reported. This family descriptor is the clone PuHu26. Hybridization of genomic DNA digested with HindIII showed that sequences homologous to PuHu26 are tandemly organized. Genomic DNA cleaved with EcoRI revealed that a subpopulation of the PuHu26 family contains EcoRI restriction sites spaced at multiples of approximately 172 bp
