Hi monkfan, you missed to quote the $go_term, it should be: 
my $sql = "SELECT Symbol FROM gene_info RIGHT JOIN gene2go ON(gene_inf
+o.GeneID=gene2go.GeneID) WHERE GO_Term='$go_term'";

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Or, the best way as can be found in the excellent manual of DBI is to use a placeholder (the ? mark). 
my $go_term = 'proteasome localization';
my $sql = 'SELECT Symbol FROM gene_info RIGHT JOIN gene2go ON(gene_inf
+o.GeneID= gene2go.GeneID) WHERE GO_Term=?';

my  $sth = $dbh->prepare($sql);
$sth->execute($go_term) or die "SQL Error: $DBI::errstr\n";

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Then you don't need to worry about quoting anymore. Oh, another thing. Get used to use single quote on plain string, e.g it doesn't contain variable or evaluable expression.
Update: gleh, fixed typo

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In reply to Re: Problem Converting SQL term to Perl Variable by naikonta
in thread Problem Converting SQL term to Perl Variable by monkfan

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