title: Purification and partial characterization of high-molecular-weight forms of ectopic calcitonin from a human bronchial carcinoma cell line.
abstract: Studies on the high-molecular-weight immunoreactive calcitonin produced ectopically in culture by an epidermoid bronchial carcinoma cell line are reported. In cell-exposed medium, the principal component has a molecular weight of 40000 and molecules of mol.wts. 13000 and 10000 also occur. Only a trace amount of material co-eluting with 35000-mol.wt. human calcitonin is detectable. None of the calcitonins show cross-reactivity with anti-corticotropin serum. The 40000-mol.wt. immunoreactive calcitonin is readily proteolysed to the 13000- and 10000-mol.wt. components, but the 10000-mol.wt. component behaves as a comparatively stable 'core' molecule. By using immunoprecipitation and high-pressure liquid chromatography (h.p.l.c.), it is possible to prepare radiochemically homogeneous 10000-mol.wt. immunoreactive calcitonin from cells grown in the presence of individual 35S- or 3H-labelled amino acids. Peptide mapping of enzymic digests of this material by h.p.l.c. shows that it contains peptides in common with synthetic human calcitonin.
mesh_terms: D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000032:analysis* / Q000473:pathology; D002116:Calcitonin / Q000302:isolation & purification*; D002460:Cell Line; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006729:Hormones, Ectopic / Q000302:isolation & purification*; D006801:Humans; D008175:Lung Neoplasms / Q000032:analysis* / Q000473:pathology; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
chemical_list: D006729:Hormones, Ectopic; D010446:Peptide Fragments; D002116:Calcitonin; D014357:Trypsin