The Anopheles gambiae “Plus-C” OBPs are distinguished from the “classic” and “atypical” OBP classes by their longer sequences and the presence of 12 cysteines in conserved positions. The “Plus-C” AgamOBP48, which displays the second highest expression level in female antennae, was shown to be down-regulated after a blood meal, a finding suggesting that protein as important determinant of the host seeking behavior of female mosquitoes