Two transcripts of the same ecdysterone-controlled gene are differentially associated with ribosomes.

The ecdysterone-controlled gene I-18C of Chironomus tentans produces two transcripts by differential splicing: a 1.8-kb RNA, with an open reading frame (ORF) of 417 nucleotides (nt) and a 4.6-kb RNA, with no ORF longer than 270 nt. Centrifugation of cytoplasmic extracts in velocity sedimentation sucrose gradients and CsCl-buoyant-density gradients demonstrates that the 1.8-kb RNA is incorporated into polysomes. The 4.6-kb RNA, however, exhibits characteristics of free ribonucleic acid-protein complexes and monosomes.