The presence of gonadotropin binding sites in the intracellular organelles of human ovaries.
The nuclei (N), plasma membranes (PM), mitochondria-lysosomes, rough endoplasmic reticulum, and combined (light, medium, and heavy) Golgi (G) fractions were isolated from human ovaries. The purities of these fractions were evaluated by assays of appropriate marker enzymes, which revealed that some fractions were very pure but that others had minor contamination. When tested, all of the fractions exhibited 125I-labeled human chorionic gonadotropin (125I-hCG)-specific binding. This intracellular 125I-hCG binding was not due to PM contamination because: (1) N, which had no detectable 5'-nucleotidase (5'-NE) activity, a marker for PM, exhibited 125I-hCG-specific binding; (2) the G, which had only a fraction of the 5'-NE activity of PM, exhibited as much binding as PM; and (3) the ratios between specific 125I-hCG binding and 5'-NE activity in other fractions were not the same as for PM. They should have been the same if PM contamination was responsible for the 125I-hCG binding observed in other organelles. In conclusion, our results demonstrate that gonadotropin-binding sites are present in various intracellular organelles as well as in PM of human ovaries.
D001665:Binding Sites; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005260:Female; D006056:Golgi Apparatus / Q000648:ultrastructure; D006801:Humans; D008247:Lysosomes / Q000648:ultrastructure; D008928:Mitochondria / Q000648:ultrastructure; D010053:Ovary / Q000648:ultrastructure*; D011506:Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure
D006063:Chorionic Gonadotropin; D011506:Proteins