#!/usr/bin/env perl -l

use strict;
use warnings;

my $line7 = '';

my $re = qr{/translation="([^"]+)"};

while (<DATA>) {
    if (/^\s+\/translation=/ .. /^\s+exon/) {
        $line7 .= $_;
    }
    else {
        $line7 ? last : next;
    }
} 

my ($extract) = $line7 =~ $re;

$extract =~ s/\s+//g;

print $extract;

__DATA__
...
                     /db_xref="GI:2735715"
                     /translation="MLSFVDTRTLLLLAVTLCLATCQSLQEETVRKGPAGDRGPRGER
                     GPPGPPGRDGEDGPTGPPGPPGPPGPPGLGGNFAAQYDGKGVGLGPGPMGLMGPRGPP

                     YASQNITYHCKNSIAYMDEETGNLKKAVILQGSNDVELVAEGNSRFTYTVLVDGCSKK
                     TNEWGKTIIEYKTNKPSRLPFLDIAPLDIGGADHEFFVDIGPVCFK"
     exon            2432..2501
...