Fig. 1

Characteristics of the HML-10 endogenous retrovirus family. a Structure of HML-10 proviruses [18]. b Estimation of the evolutionary age of HML-10 with divergence times as reported before [78]. The box-and-whiskers plot shows age estimation by sequence comparison of LTRs from six complete proviruses (elements nos. 1, 3, 20, 22, 25 and 68 in Table 1) in the human genome [28]. The arrowhead indicates the integration events in the OWM lineage. c Neighbor-joining tree of Pol protein sequences of different endogenous and exogenous betaretroviruses [18, 72]. The horizontal bar represents 0.1 substitutions per amino acid position. d Chromosomal distribution of HML-10 elements in the human genome. Details can be found in Table 1. e Comparison of genomic fractions of intragenic elements (located within the boundaries of RefSeq [33] genes) between HML-10 and other HERV families in the human genome. All observed distributions differed significantly from the expected value for random integration that is shown as dotted horizontal line, with P-values ≤ 0.01 inferred by chi-square tests