SOLUBILIZATION AND CHARACTERIZATION OF THE CHICKEN OOCYTE VITELLOGENIN RECEPTOR

This paper describes the biochemical characterization of the chicken oocyte plasm-membrane receptor for one of the major lipid-carrying yolk proteins, vitellogenin (VTG). The receptor was extracted from oocyte membranes with the non-ionic detergent octyl-.beta.-D-glucoside and visualized by ligand blotting, with 125IVTG as a protein with an apparent Mr of 96,000, under non-reducing conditions. It exhibited high affinity for native chicken VTG (Kd 2 .times. 10-7 M) but was unable to bind VTG with reductively methylated lysine residues or phosvitin (the phosphoserine-rich intracellular cleavage product of VTG). Polyclonal antibodies to the 96 kDa protein inhibited VTG binding to the receptor and were able to precipitate functional VTG-receptor activity from oocyte-membrane detergent extracts with a concomitant removal of the 96 kDa protein. Antibodies directed against the mammalian receptor for low-density lipoprotein showed crossreactivity with the chicken oocyte VTG receptor, raising the possibility that lipoprotein receptors in birds are structurally related to those in mammalian species.