Characterization of Tissue-Ferritin Purified from Wax Moth, Galleria mellonella

Tissue-ferritin was homogeneously purified from the hemolymph-free whole body of Galleria mellonella larvae. Tissue-ferritin was composed of four subunits, 26, 30, 32 and 34 kDa. The 34 kDa subunit among them was specifically found in tissue ferritin while its N-terminal sequence of 19 amino acid residues was identical to that of 32 kDa hemolymph-ferritin subunit. It was observed that the 32 and 34 kDa subunit of tissue-ferritin were glycosylated like 32 kDa subunit of hemolymph-ferritin. It suggests that the 34 kDa subunit is an isoform of 32kDa ferritin subunit according post-transcriptional modification. By semi quantitative RT-PCR, the distribution of 32 kDa ferritin subunit mRNA was observed in fat body, Malpighian tubules, integument, and muscle, but found in a very small amount in silk gland or not found in gut. On the other hand, 26 kDa subunit mRNA was found in all organs tested although it was in a small quantity found in gut and silk gland. By dietary Hg treatment, 34 kDa subunit of tissue-ferritin was clearly up-regulated.