Mass-spectrometric identification of binding proteins of Mr 25,000 protein, a part of vitellogenin B1, detected in particulate fraction of Xenopus laevis oocytes.
A phosphorylated protein with molecular mass of 25,000 (pp25) is a component of Xenopus laevis vitellogenin B1. Our previous report showed the existence of several binding proteins of pp25 in the particulate fraction of Xenopus oocytes. In an attempt to elucidate the function of pp25, two of these binding proteins were purified, analyzed by mass-spectrometry, and identified as ribosomal proteins S13 and S14. Other binding proteins in the particulate fraction mostly corresponded to those derived from purified 40S and 60S ribosomal subunits, as shown by the overlay assay method. However, pp25 did not show any effect on protein synthesis in the rabbit reticulocyte lysate system. A model in which pp25 connects a type of serpin (serine protease inhibitor), the only pp25-binding protein detected in the cytoplasm, to the endoplasmic reticulum through two serine clusters is proposed to explain a possible function of this protein.
Sugimoto
Isamu
I
Department of Biomedical Sciences, School of Life Sciences, Faculty of Medicine, Tottori University, Yonago 683-8503, Japan.
Li
Zhijun
Z
Yoshitome
Satoshi
S
Ito
Susumu
S
Hashimoto
Eikichi
E
D000818:Animals; D003593:Cytoplasm / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000737:chemistry; D013058:Mass Spectrometry; D008970:Molecular Weight; D009865:Oocytes / Q000737:chemistry*; D011485:Protein Binding; D014819:Vitellogenins / Q000737:chemistry* / Q000378:metabolism; D014982:Xenopus laevis
D014819:Vitellogenins