Abstract
A recently described method to investigate hGH receptors on circulating human blood cells has been used to study the effect of trypsin and antitrypsin on hormone binding to mononuclear cells. Trypsinization of cells lead to a considerable decrease of specific binding and of binding affinity (affinity constant after 60 minutes trypsinization 0.5×109 M−1 versus 1.5×109 M−1 in untreated control cells). Exposure of peripheral mononuclear cells to antitrypsin activities was followed by a steady increase of affinity and specific binding (affinity constants: with 10 KIU 1.9×109 M−1, with 100 KIU 2.4 × 109 M−1, with 1000 KIU 3.6×109 M−1). This antitrypsin effect exceeds the binding values expected after blocking trypsin activities in the incubation medium. In a subset of experiments somatomedin-B was used as the antitrypsin moiety and was shown to increase specific GH binding in a similar manner as did antitrypsin (with 1000 ng SM-B affinity constant 12.0×109 M−1, specific binding 9.7 % of total radioactivity). It is concluded that enzymatic factors and their inhibitors including partially GH dependent moieties like somatomedin-B modulate GH-induced action by regulating specific GH receptors in GH target tissues.
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Kiess, W., Butenandt, O. 38 EFFECT OF TRYPSIN AND ANTITRYPSIN ON SPECIFIC BIWDING OF HGH TO HUMAN PERIPHERAL MONONUCLEAR CELLS. Pediatr Res 19, 609 (1985). https://doi.org/10.1203/00006450-198506000-00058
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DOI: https://doi.org/10.1203/00006450-198506000-00058