Tissue Ferritin (Ft) is a 450,000 Da iron storage protein, made up to 24 L or H subunits (19 kDa and 21 kDa respectively), which is found in most mammalian cells. Heart Tissue synthesizes a novel form of Ft which has a lower MW (180,000 Da), lower iron content and atypical subunits of 45 kDa, 55 kDa and 65 kDa. Based on these data, low MW heart Ft is similar to serum ferritin. The investigators have previously shown by Northern blot analysis that mRNA coding for Ft is present on endoplasmic reticulum-bound ribosomes in rat heart tissue. This suggests that a portion of Ft in heart is destined for secretion, perhaps by a mechanism similar to that for the secretion of atrial natriuretic factor. Taken together these data suggest that heart is the site of synthesis of serum Ft. In order to explore this possibility and determine the structural relationship between low MW heart Ft and serum Ft, the investigators will purify both ferritins and their subunits will be sequenced by thermospray LC/mass spectroscopy. In addition, the position of any asn-linked oligosaccharide side chains will be determined by peptide mapping of Ft subunits treated with Glyconase G.
| Campbell, C H; Crocker, D; Gruntmeir, J J et al. (1993) Purification of a novel glycosylated ferritin from horse heart. J Cell Biochem 53:420-32 |
