Comparison of transferrin sequences. Putative iron-binding residues are shadowed and indicated by the stars. Conserved cysteine residues are indicated by the dots. Hutf, human transferrin (GenBank/EMBL accession number M12530); Hltf, human lactoferrin (X53961); Sptf, flesh fly (Sarcophaga peregrina) transferrin (D28940); Aatf, mosquito (Aedes aegypti) transferrin (AF019117); Bdtf, cockroach (Blaberus discoidalis) transferrin (L05340); Mstf, moth (Manduca sexta) transferrin (M36296). The conserved regions in insect transferrins used for designing of PCR primers are underlined.