Formation of circular polyribosomes in wheat germ cell-free protein synthesis system.
We report a morphological study of functioning ribosomes in a efficient and robust cell-free protein synthesis system prepared from wheat embryos. Sucrose density gradient analysis of translated mixtures programmed with luciferase mRNAs having different 5' and 3' untranslated regions showed formation of large polysomes. Electron microscopic examination of translation mixtures programmed with those of capped and polyadenylated mRNA revealed that ribosomes assemble into a circular-type polysome in vitro. Furthermore, a series of experiments using mRNAs lacking either cap, poly(A) tail or both also resulted in the formation of circular polysomes, which are indistinguishable from those with the original mRNA. The wheat germ cell-free system may provide a good experimental system for understanding functional ribosomes at the molecular level.
Madin
Kairat
K
Cell-free Science and Technology Research Center, and The Venture Business Laboratory, Ehime University, Matsuyama 790-8577, Japan.
Sawasaki
Tatsuya
T
Kamura
Nami
N
Takai
Kazuyuki
K
Ogasawara
Tomio
T
Yazaki
Kazumori
K
Takei
Toshiaki
T
Miura
Kin-Ichiro
K
Endo
Yaeta
Y
D002474:Cell-Free System; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism* / Q000648:ultrastructure; D014176:Protein Biosynthesis; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D014908:Triticum / Q000166:cytology / Q000502:physiology*
D010940:Plant Proteins; D012333:RNA, Messenger