Wheat-embryo ribonucleates. I. Subcellular localization of a satellite polyribonucleotide.

Abstract

(1) When wheat embryos are extracted with aqueous phenol and the aqueous phase is made 2.5 M with respect to NaCl at 0 °C, there is selective precipitation of about 80% of the total RNA. The 18 S and 26 S RNA species from the wheat-embryo ribosomes comprise a preponderant mass fraction (ca. 80%) of this NaCl-insoluble RNA (iRNA). A small amount of a rapidly migrating electrophoretic component (iRMEC) can be released by aqueous denaturation of wheat-embryo NaCl-insoluble RNA and because it is specifically complexed with 26 S RNA, the iRMEC component has been termed a "satellite" of 26 S RNA.(2) The wheat-embryo satellite RNA has been shown to be present in the microsomal fraction recovered from cell-free homogenates of wheat embryos.(3) The wheat-embryo satellite RNA has been shown to be differentially localized in the large subunit of wheat-embryo ribosomes where it presumably exists as part of the same intermolecular 26 S RNA complex that can be isolated by directly extracting the whole embryos with aqueous phenol.(4) During preparation of the ribosomal subunits, there is substantial degradation of the component ribonucleates and the nature of this degradation is the subject of a brief discussion.