Identification of vitellogenin receptors in the ovary of a teleost fish, the Mediterranean sea bass (Dicentrarchus labrax)

― The characterization of vitellogenin (VTG) receptors in ovarian membranes from vitellogenic female sea bass (Dicentrarchus labrax) is described. Incubation of mem- brane proteins with radiolabeled VTG ( 125 I-VTG) after SDS-electrophoresis showed specific binding of 125 I-VTG to a protein band of 100 kDa. Filter binding assays showed that binding of 125 I-VTG to membrane receptors was saturable with increasing amounts of 125 I_VTG. Scatchard analysis of the saturation data revealed a single class of binding sites with an apparent K D of 1.04.10-8 M. The specificity of the VTG receptors was tested in competition assays; binding of 125 1-VTG to ovarian membranes was completely abolished with an excess of purified sea bass VTG (cold VTG, VTG) or plasma from estradiol (E2)-treated fish, while the addi- tion of control male plasma (without VTG) caused negligible effect. teleost / sea bass / Dicentrarchus labrax / vitellogenin / receptor Rsum ― Identification du rcepteur la vitellognine dans l'ovaire d'un poisson tlos- ten, le bar mditerranen (Diceutrarchus labrc!r). Les rcepteurs la vitellognine (VTG) ont t caractriss dans des membranes de l'ovaire de bar (Dicentrarchus labrax) en vitello- gense. L'incubation des protines membranaires avec la VTG marque (!25I-VTG) aprs SDS-lectrophorse montre une liaison spcifique de la ' 25 1-VTG une bande protique de