Keegan B P, Sheflin L G, Spaulding S W
Department of Physiology, State University of New York at Buffalo, Buffalo, New York, 14215, USA.
Biochem Biophys Res Commun. 2000 Jan 27;267(3):881-6. doi: 10.1006/bbrc.1999.2034.
The EGF receptor in waved-2 mice contains a point mutation that renders it kinase-deficient. We investigated how the waved-2 mutation affects the internalization and endosomal trafficking of the receptor in vivo in response to EGF. When the waved-2 mice were injected with EGF, there was approximately 50% less tyrosine phosphorylation detected in whole-liver homogenate compared to wild-type background mice. Although EGF increased the EGF receptor levels in the early and late liver endosomal fractions of waved-2 mice, its trafficking was delayed compared to wild-type mice. Ubiquitination of the EGF receptor may affect its endosomal sorting. We found that a similar amount of EGF receptor was immunoprecipitated from the endosomal fractions of EGF-treated waved-2 and wild-type with anti-ubiquitin antibody. These results demonstrate that the waved-2 EGF receptor can become ubiquitinated and can be trafficked to the late endosomes, although it appears that its kinase deficiency delays this process.
波状毛-2小鼠中的表皮生长因子（EGF）受体含有一个点突变，使其激酶功能缺陷。我们研究了波状毛-2突变如何影响该受体在体内对EGF的内化和内体运输。给波状毛-2小鼠注射EGF后，与野生型背景小鼠相比，全肝匀浆中检测到的酪氨酸磷酸化减少了约50%。虽然EGF增加了波状毛-2小鼠肝脏早期和晚期内体组分中的EGF受体水平，但其运输与野生型小鼠相比有所延迟。EGF受体的泛素化可能会影响其在内体中的分选。我们发现，用抗泛素抗体从经EGF处理的波状毛-2和野生型小鼠的内体组分中免疫沉淀出的EGF受体数量相似。这些结果表明，波状毛-2 EGF受体可以被泛素化，并可以运输到晚期内体，尽管其激酶缺陷似乎会延迟这一过程。
