Tunicamycin-inducible polypeptide synthesis during Xenopus laevis embryogenesis.
Tunicamycin treatment of Xenopus laevis embryos enhanced the synthesis of a specific set of polypeptides with molecular masses of 98, 78, 59 and 58 kDa. The 78-kDa polypeptide was tentatively identified as glucose-regulated protein (GRP) 78 on the basis of molecular mass, pl (5.2), and tunicamycin inducibility, which took place upon treating embryos after the midblastula transition (MBT). The synthesis of a polypeptide with this electrophoretic mobility was detected but was not tunicamycin-inducible at stages prior to the MBT. GRP78 mRNA was detectable before the MBT but was not inducible by tunicamycin until the tailbud stage. A comparison of tunicamycin-induced polypeptide synthesis in Xenopus embryos, A6 cell line, and white blood cells by 2D-PAGE and fluorography revealed three spots in the GRP78 region of the gel. One was observed in both embryos and adult cells; another was adult-specific; and the third one was possibly an embryo-specific form. These results suggest that GRP78 synthesis might undergo a switch from an embryonic to an adult pattern during Xenopus development.
Department of Biology, University of Waterloo, Ontario, Canada.
R S
RS
Winning
N C
NC
Bols
J J
JJ
Heikkila
D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000096:biosynthesis; D015180:Electrophoresis, Gel, Two-Dimensional; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D005775:Gastrula / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis*; D018832:Molecular Chaperones; D014176:Protein Biosynthesis; D014415:Tunicamycin / Q000494:pharmacology*; D014982:Xenopus laevis / Q000378:metabolism*
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; C018551:glucose-regulated proteins; D014415:Tunicamycin