The sequence that you
entered was filtered by the BLAST program.
The filtering has the effect
of replacing regions of your input sequence of low structural complexity
with “N” (or “X” for amino-acid sequences). For details on filtering,
see the section “FILTER” in the BLAST HELP. To
disable filtering, select the OFF radio button in the “FILTER” option in
the lower portion of the Settings screen.
Note with caution that setting
this option to “OFF” may result in search times that are longer than
normal.