Determination of the criteria of identity value and overlapping length in grouping condition. We classified 213,404 mouse 3′ end sequences in light of the results of homology searches using BLASTsoftware (Pearson and Lipman 1988) to determine the criteria of grouping. (A) Clones whose end sequences were more similar than the identity threshold were placed together. Here, the identity threshold varied from 80% to 98%. The number of resulting groups increased as the identity threshold increased from 90%; therefore, an identity threshold of 90% is appropriate for placing similar sequences together. (B) Clones whose end sequences exceeded the overlap threshold were placed in the same group. In this example, the overlap threshold varied from 20 to 200 bp. The number of resulting groups was almost constant between 30 and 150 bp; therefore, an overlap threshold of 30 to 150 bp is appropriate for grouping.
