use strict;
use warnings;

while ( <DATA> ) {
  s/([^"])(,\w*,\w*,ResGen,)/$1"$2/;
  print;
}

__DATA__
GENE1="Rattus norvegicus serum and glucocorticoid-regulated kinase (sgk) mRNA, complete cds,NM_019232,333,ResGen,ATP binding|protein serine/threonine kinase|protein amino acid phosphorylation,,,,29517
GENE2="ESTs, Weakly similar to putative serine/threonine protein kinase MAK-V [M.musculus]",NM_144755,331,ResGen,,,,,246273
GENE3="Thiosulfate sulphurtransferase (rhodanese)",X56228,329,ResGen,mitochondrion|sulfate transport|thiosulfate sulfurtransferase,,,,25274
GENE4="Spleen tyrosine kinase,NM_012758,327,ResGen,ATP binding|protein tyrosine kinase|intracellular signaling cascade|protein amino acid phosphorylation,,,,25155
GENE5="Spleen kinase 24,NM_012758,,ResGen,ATP binding|protein tyrosine kinase|intracellular signaling cascade|protein amino acid phosphorylation,,,,25155