>perl -wMstrict -le
"my $seq = 'xxxTATAATGyyyTatAtAtzzz';
 my $box = qr{ (?i) TATA [TA] [TA] [TAG] }xms;
 ;;
 my @TATAs;
 while ($seq =~ m{ ($box) }xmsg) {
   push @TATAs, [ $1, $-[1], ];
   }
 ;;
 print qq{matched '$_->[0]' at pos $_->[1]} for @TATAs;
"
matched 'TATAATG' at pos 3
matched 'TatAtAt' at pos 13