Isolation, characterization, and radioimmunoassay of murine egasyn, a protein stabilizing glucuronidase membrane binding.

摘要: Glucuronidase present in lysosomes of mouse liver occurs as the free tetramer, whereas glucuronidase endoplasmic reticulum macromolecular complexes containing one to four molecules protein egasyn. Earlier genetic and biochemical studies suggest that these complexes, or M forms, function stabilize membrane binding glucoronidase. The detergent Triton X-100 extracts glucuronidase-egasyn intact they dissociate presence deoxycholate upon heating. We have now purfied egasyn by releasing it from antiglucuronidase immunoprecipitates forms under relatively mild conditions, such treatment with heating at 50 degrees. Isolated is a glycoprotein molecular weight about 64,000 not unusually hydrophobic amino acid composition. Monospecific antibody was raised. This showed no cross-reactivity purified beta-glucuronidase failed react egasyn; however, both antibodies bound egasyn-glucuronidase complexes. A procedure for radioimmunoassay developed utilizing labeled iodine 125. Most antigenic sites homogenates normal are masked after extraction only become immunoreactive exposure deoxycholate. After unmasking, proved contain 56 mug egasyn/g, nearly all which localized microsomal fraction. Of this total 10% complexed glucuronidase, suggesting theat bulk may be other proteins. Mice inbred strain YBR, carry EgO mutation resulting absence lacked egasyn, primary defect lies unavailabililty agasyn form There considerable evidence support concept exist membranes formation required maintenance membranes. Egasyn represent class anchor proteins each charcteristic set