Expression of the mitochondrial genome in HeLa cells

摘要: Abstract The fraction of mitochondrial DNA which is complementary to mitochondria-associated RNA in exponentially growing HeLa cells has been investigated by RNA-DNA hybridization experiments using strands separated alkaline CsCl density-gradient centrifugation and from uniformly labeled with [5- 3 H]uridine. It found that hybridizes almost exclusively the heavy strand, agreement complementarity their base compositions. Less than 2% light after purification two cycles gradient centrifugation, was form hybrids RNA. In saturation experiments, sedimenting slower 22 s or faster 30 gave about 100% level, whereas components intermediate range sedimentation coefficients 85% level. An analysis Cs 2 SO 4 gradients density formed at showed less greater banded a 1.491 g/cm , i.e. expected for fully base-paired hybrids; slightly lower (1.485 ), level obtained these components. electron microscopy essentially all material band consists nucleic acid duplexes. view available evidence absence major internal repetitions mammalian DNA, results three approaches described here indicate whole genome transcribed cells. possibility this transcription occurs continuous chain discussed.