| 1. |
- Löfberg, H, et al.
(författare)
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gamma-trace in human pituitary adenomas
- 1984
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 59:1, s. 8-113
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Tidskriftsartikel (refereegranskat)abstract
- gamma-Trace, a small protein occurring in body fluids and in secretory and neuroendocrine cells, was demonstrated by immunohistochemical techniques in the cytoplasm of the tumor cells of 13 pituitary adenomas obtained at surgery and autopsy. Seven of the adenomas also contained LH immunoreactivity. FSH, TSH, and ACTH were each found in one gamma-trace-containing adenoma. gamma-Trace was also demonstrated in extracts of 1 pituitary adenoma and of 5 nontumorous adenohypophyses. The immunoreactive protein found in the extracts had a molecular weight and electrophoretic mobility characteristic of gamma-trace. Computerized amino acid sequence comparisons between the primary structure of gamma-trace and those of known hormonal peptides showed no significant similarities.
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| 2. |
- Wallén, P, et al.
(författare)
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Purification and characterization of a melanoma cell plasminogen activator.
- 1983
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Ingår i: European Journal of Biochemistry. - 0014-2956 .- 1432-1033. ; 132:3, s. 681-6
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Tidskriftsartikel (refereegranskat)abstract
- The plasminogen activator from a human melanoma cell line was purified with immunoadsorption as a major step. The cells were cultured in the presence of aprotinin in order to avoid proteolysis. A three-step purification involved adsorption on antibodies to porcine tissue plasminogen activator before chromatographies on arginine-Sepharose and Sephadex G-150. All solvents contained Tween-80 (0.01%) and, except for the last step, aprotinin. The final product had a specific activity of about 220000 IU/mg measured against the WHO urokinase standard. The activator obtained has an apparent Mr of 72000 and consists of single-chain molecules. Evidence was obtained that four different types of activator variants occur. First and known previously, the one-chain form can be proteolytically cleaved into a two-chain form. Secondly, both the one-chain and two-chain molecules exhibit two forms with molecular weight differences of about 3000 (possibly due to carbohydrate differences). Thirdly, the one-chain preparations contain two variants, each constituting about 50% of the material and differing in length by three N-terminal amino acids. Finally, a possible positional microheterogeneity was detected. Digestion with plasmin yields the two-chain form with disulfide-bonded polypeptide chains, 'A' and 'B' (from the N-terminal and C-terminal parts, respectively). At the same time, the variability of the original N terminus is removed. The A chain keeps the two Mr variants (now about 40000 and 37000, respectively). The B chain (Mr about 33000) contains the active site of the molecule, as demonstrated by labelling with [3H]diisopropyl phosphofluoridate, and is homologous to the enzymatically active chains of thrombin, plasmin and other serine proteases. In contrast to these enzymes, the plasminogen activator is enzymatically active in the one-chain form. A speculative explanation for this activity may possibly be the presence of an epsilon-amino group of a lysine residue at a position close to the bond cleaved in the two-chain form.
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