Not sure how stable is the file structure, maybe you really should write a parser, as suggests JavaFan, but the following example would work on the given input: 

use strict;
use warnings;

open my $fh, "<", "file.frg";

while(<$fh>) {
    if (/^{FRG/../^}/){
        if (/^acc:(\d+)/) {
            print ">$1\n";
        }
        elsif ( /^seq:/ ) {
            while(<$fh>) {
                last if /^\./;
                print;
            }
        }
    }
}

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In reply to Re: Vertical Regex by zwon
in thread Vertical Regex by joomanji

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