title: Increased binding of concanavalin A at the cell surface following exposure to thyroliberin.
abstract: Thyroliberin (THR) binds specifically to SD1 rat prolactin cells and increases prolactin release. THR-induced modifications of surface membrane of intact SD1 cells were looked for, using concanavalin A (Con A) as a probe. At the electron microscope level the binding was restricted to the cell surface. Preexposure of the cells to TRH (27 nM) for 30 min at 37 degrees C increased the binding of Con A by 28--120%. Such an increase was not observed with low doses of TRH (13.5 and 2.7 nm) nor after only a 10-min exposure to 27 nM TRH. This effect is specific for TRH; it was not observed with other peptiDES. Simultaneous exposure to Con A and [3H] TRH did not alter [3H]TRH binding, but preexposure to Con A reduced the [3H]TRH binding by 10%, which may be due to steric hindrance. It is concluded that TRH induces an increased exposure of surface membrane glycoproteins in intact SD1 cells.
mesh_terms: D002460:Cell Line; D006023:Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D011952:Receptors, Concanavalin A / Q000187:drug effects* / Q000378:metabolism; D011955:Receptors, Drug / Q000187:drug effects*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
chemical_list: D006023:Glycoproteins; D008565:Membrane Proteins; D011952:Receptors, Concanavalin A; D011955:Receptors, Drug; D013973:Thyrotropin-Releasing Hormone