use strict;
use warnings;

my $str = 'GVGFTVILISFKYVGFFYNVIIAWALHYFFSSFTMDLPRWIHCNNTWNSPNCSDAHASNSSDGLGLNDTFGTTPAAEYFER';
my @segments = map {[$_, (scalar tr/STY//)]} split /(?<=[KR])/, $str;

printf "%45s: %d\n", @$_ for @segments;