Biopolymers and cell. 1992; 8 (3): 9 -19

ISKAKOV B. MADIN K. I.

Characterization of 45S RNA-Particles From Wheat Embryos

Summary

    Relatively homogeneous 45S ribonucleoprotein particles, containing considerable amount of a newly synthesized rapidly labeled RNA, have been detected in subribosomal fraction of cytoplasmic extract from germinating wheat etbryos. These particles have the buoyant density of about 1.50 g/cm3 and apparently are not represented by free cytoplasmic informosomes. The isolated particles contain 17S rRNA, rapidly labeled heterogeneous (6—16S) RNA with strong messenger activity and severall low molecular weight RNAs among which the 5*3S RNA (of about 135 nt) is the most uabndant. According to 2D-PAGE two groups of polypeptides can be revealed in the particles. Polypeptides of the first group (10—50 kDa) correspond to structural ribosomal proteins. The second group consists of higher molecular weight polypeptides (40— 120 kDa) and may include polypeptides of translation initiation factors. The 45S particles may represent a native [mRNP*40S*eIFs*Met-tRNAi*GTP] complex which may occur in vivo as a translatable intermediate in the initiation sequence.