Fig. 2

a. Distribution of 3′ and 5′ flank length (fragmentation by FspBI and Csp6I restrictases) of reference hg38 full-sized insertions belonging to active Alu subgroups (AluYa5 and AluYb8). 25–800 bp long flank is suitable for Illumina sequencing and correct mapping to the human genome. b. Scheme of TSD (Target Site Duplication) identification principle. 5′ and 3′ flank library reads are independently mapped to the reference human genome. Integration point of each insertion is situated between nearest restriction sites. Pairs of 5′ and 3′ library reads belonging to the same insertion are detected using genomic coordinates of mapped reads ends and expected nearest restriction site. c. Weblogo diagram of nucleotide frequencies in identified TSD and integration sites (see Additional file 2) of previously unknown Alu insertions used for the method testing. TSD identification was performed using sequences of 5′ and 3′ flank libraries. d. TSD length (see Additional file 2) distribution for Alu insertions used for the method testing. e. Poly-A tail length (see Additional file 2) distribution for Alu insertions used for the method testing