CHARGE POLYMORPHISM IN HUMAN LUNG-CELL PRO-CATHEPSIN-B

Secreted pro-cathepsin B of HS-24 human lung-tumour cells, human alveo lar macrophages and Wi-38 human lung-fibroblast cells was pre-purified by ion exchange hromatography and investigated by 2D gel electrophore sis. Four (Wi-38), six (HS-24) and ten (alveolar macrophages) polypept ides differing in charge, but with the same molecular mass of 45 kDa, were found. The isoelectrical points of these polypeptides ranged from 5.43 to 6.57. Deglycosylation reduced the mass (7 kDa) but did not ch ange the charge pattern. This investigation established cell type-spec ific patterns of secreted pro-cathepsin B-forms, but only parts of the se may be cell type-specific forms depending on differentiated express ion of mRNA and post-translational modification.