Presence of a putative 15S precursor to β-globin mRNA but not to α-globin mRNA in Friend cells

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Abstract
Dimethyl sulfoxide-induced Friend cells [leukemia] were labeled for periods of 5-60 min. The denatured RNA was fractionated by sucrose gradient centrifugation and the distribution of .alpha.- and .beta.-globin specific [3H]RNA was determined by hybridization to hybrid plasmids containing mouse .alpha.- and .beta.-globin DNA, respectively. After 5 min of labeling, a 15S peak of .beta.-globin specific (but not .alpha.-globin specific) [3H]RNA was detected, next to an equal amount of 10S .beta.-globin [3H]RNA. With increasing periods of labeling, the amount of 15S .beta.-globin [3H]RNA remained constant but the amount 10S .beta.-globin [3H]RNA increased steadily. .alpha.-Globin specific [3H]RNA sedimented at 11S after 5 min of labeling and at 9.5S after longer labeling periods. Analysis of 15S globin specific [3H]RNA purified by the poly(dC)-cDNA method showed oligonucleotides characteristic of .beta.-globin mRNA, but not .alpha.-globin mRNA, and about 20 new oligonucleotides. The results suggest that 10S .beta.-globin mRNA arises via a 15S precursor that has a half-life of 5 min or less; 9.5S .alpha.-globin mRNA may be derived from an 11S precursor.