Andrews S C, Treffry A, Harrison P M
Department of Biochemistry, University of Sheffield, U.K.
Biochem J. 1987 Jul 15;245(2):447-53. doi: 10.1042/bj2450447.
Ferritin present within siderosomes of iron-loaded rats has a faster anodal mobility than that of cytosolic ferritin from the same rats. A 19-amino-acid-residue peptide was isolated from this fast ferritin and shown to be derived from the C-terminal end of its L-subunit. A 17.3 kDa peptide seen on electrophoresis in denaturing gels of this ferritin accounts for the major portion of the original 182-residue subunit. The two peptides arise from cleavage within the 'insertion region' of the L-subunit sequence that occurs between the D and E helices and lies on the outside of the assembled molecule. This cleavage is present in about 80% of the L-subunits of siderosomal ferritin but nevertheless leaves the molecular structure otherwise intact. It gives rise to an apparent decrease in molecular size, accounting for the faster anodal mobility on native gels. Hence a new form of heterogeneity in ferritin preparations has been explained.
铁负荷大鼠的铁小体中的铁蛋白，其阳极迁移速度比同一大鼠胞质铁蛋白的迁移速度快。从这种快速迁移的铁蛋白中分离出一个由19个氨基酸残基组成的肽段，结果表明它来源于其L亚基的C末端。在这种铁蛋白的变性凝胶电泳中出现的一个17.3 kDa的肽段，占原来182个残基亚基的主要部分。这两个肽段是由L亚基序列中位于D螺旋和E螺旋之间、且在组装分子外部的“插入区域”内的切割产生的。这种切割存在于约80%的铁小体铁蛋白L亚基中，但分子结构的其他部分仍保持完整。它导致分子大小明显减小，这就解释了在天然凝胶上阳极迁移速度更快的原因。因此，铁蛋白制剂中一种新的异质性形式得到了解释。
