MOLECULAR CHARACTERIZATION OF AN INSECT TRANSFERRIN AND ITS SELECTIVEINCORPORATION INTO EGGS DURING OOGENESIS

A protein with a molecular mass of 65 kDa that was specifically taken up into eggs was purified from the hemolymph of adult female Sarcophag a peregrina flies. From cDNA analysis, this protein was shown to be a Sarcophaga transferrin. Unlike mammalian transferrin, the similarity b etween its N-terminal and C-terminal halves was only 19%, and it was s uggested to conjugate one iron atom/molecule in its N-terminal half. S arcophaga transferrin was found to transport iron ions into eggs durin g oogenesis and deliver them to another protein, thought to be ferriti n. No significant activation of the transferrin gene was detected duri ng embryogenesis, so probably maternal transferrin is used as an inter cellular or intracellular iron-transporter during embryogenesis of thi s insect.