title: Polyribosomes and messenger RNA from rat liver mitochondria.
abstract: Rat liver mitochondrial polyribosomes were isolated free from cytoplasmic ribonucleoprotein contaminations in a number of criteria (sedimentation and buoyant density patterns, ribosomal RNA composition). Heterogeneous poly A containing RNA from mitochondrial polysomes was purified by two-stage cellulose chromatography. This RNA was in vitro labelled with 125I up to specific activity approximately 10(6)-10(7) cts.min-1.microng-1 and used for hybridization experiments with separate complementary strands of mitochondrial DNA and nuclear DNA fragments. The proportions of mitochondrial poly A containing RNA that is complementary to heavy and light strands of mtDNA were respectively 31.5% and 8.3%. Besides, a significant RNA fraction was complementary to unique sequences of nuclear DNA (2-3 copies per haploid genome). The hybrids that were formed possessed a high Tm indicative of a perfect base pairing. A dual intracellular origin of mitochondrial messenger RNA is discussed.
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D008970:Molecular Weight; D009691:Nucleic Acid Denaturation; D009693:Nucleic Acid Hybridization; D009695:Nucleic Acid Renaturation; D011061:Poly A / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D051381:Rats; D013056:Spectrophotometry, Ultraviolet
chemical_list: D012333:RNA, Messenger; D012335:RNA, Ribosomal; D011061:Poly A; D004247:DNA