The effect of HeLa cell cytoplasm on the rate of sedimentation of RNA.

Ordinarily, sedimentation analysis of RNA preparations is carried out in simple aqueous solutions. Recently, numerous investigators have carried out experiments where RNA's in cytoplasmic extracts from various types of cells have been analyzed by sedimentation through gradients of sucrose. The implicit assumption has been made that the presence of the cytoplasmic extract does not in itself affect the rate of sedimentation of the RNA. However, we have recently found that some component of HeLa cell cytoplasmic extracts causes a 1.5-2-fold increase in the sedimentation rate of a number of species of RNA. Since this result bears on the interpretation of many types of experiments, we will report the phenomenon at this time, even though we know little about its mechanism.