A block to the intracellular transport and assembly of hepatitis B surface antigen polypeptides in Xenopus oocytes.
Hepatitis B surface antigen is the major protein of the virion envelope, and is also independently secreted from infected cells as a subviral particle composed exclusively of HBsAg and host-derived lipid. Similar particles are efficiently assembled and secreted by cultured mammalian cells transfected with the gene for HBsAg. In contrast to such cultured cells, Xenopus oocytes microinjected with HBsAg mRNA secrete less than 5% of newly synthesized HBsAg polypeptides. We have examined the HBsAg biosynthetic intermediates in such oocytes and provide evidence that the impaired secretion of HBsAg is due to a discrete block in the assembly of lipoprotein particles.
Simon
K
K
Department of Microbiology, University of California Medical Center, San Francisco 94143.
Lingappa
V R
VR
Ganem
D
D
D000818:Animals; D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006514:Hepatitis B Surface Antigens / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008845:Microinjections; D008970:Molecular Weight; D009865:Oocytes; D011499:Protein Processing, Post-Translational; D014982:Xenopus laevis
D006023:Glycoproteins; D006514:Hepatitis B Surface Antigens; D008562:Membrane Glycoproteins