Winning R S, Bols N C, Heikkila J J
Department of Biology, University of Waterloo, Ontario, Canada.
Differentiation. 1991 Apr;46(3):167-72. doi: 10.1111/j.1432-0436.1991.tb00878.x.
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.
衣霉素处理非洲爪蟾胚胎可增强一组特定多肽的合成，这些多肽的分子量分别为98、78、59和58 kDa。基于分子量、等电点（5.2）和衣霉素诱导性，初步将78 kDa的多肽鉴定为葡萄糖调节蛋白（GRP）78，衣霉素诱导性是在囊胚中期转换（MBT）后处理胚胎时出现的。在MBT之前的阶段可检测到具有这种电泳迁移率的多肽的合成，但不受衣霉素诱导。GRP78 mRNA在MBT之前即可检测到，但直到尾芽期才受衣霉素诱导。通过二维聚丙烯酰胺凝胶电泳（2D-PAGE）和荧光自显影对衣霉素诱导的非洲爪蟾胚胎、A6细胞系和白细胞中的多肽合成进行比较，在凝胶的GRP78区域发现了三个斑点。一个在胚胎和成年细胞中均观察到；另一个是成年特异性的；第三个可能是胚胎特异性形式。这些结果表明，在非洲爪蟾发育过程中，GRP78的合成可能会从胚胎模式转变为成年模式。
