The growth hormone-like factor produced by the tapeworm Spirometra mansonoides specifically binds receptors on cultured human lymphocytes.
Plerocercoid larvae of the tapeworm Spirometra mansonoides produce a factor with activities similar to those of growth hormone (GH). Highly selective receptors for GH have been described on cultured human lymphocytes (IM-9 cells) and these cells have been used as a model of binding essentially restricted to human GH (hGH). We compared the displacement of [125I]hGH by hGH and partially purified plerocercoid growth factor (PGF) in assays using rabbit hepatic membranes and IM-9 cells. PGF displaced [125I]hGH from both rabbit hepatic membranes and IM-9 cells in a dose-dependent manner (r greater than 0.98). These results show that PGF specifically binds to hGH receptors on human IM-9 cells and suggest the possibility that PGF will have somatotropic activity in humans.
Phares
C K
CK
Department of Biochemistry, University of Nebraska Medical Center, Omaha 68105.
Watts
D J
DJ
D000818:Animals; D001667:Binding, Competitive; D002478:Cells, Cultured; D002589:Cestoda / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D006133:Growth Substances / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008099:Liver / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D011817:Rabbits; D011986:Receptors, Somatotropin / Q000378:metabolism*; D013146:Spirometra / Q000378:metabolism*
D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D011986:Receptors, Somatotropin; C043871:plerocercoid growth factor; D013006:Growth Hormone