Previously we uncovered a 0.45-kb transcript within the 3' end transcribed untranslated region (3'UTR) of actin gene at 5C3-4 (act5C) of Drosophila melanogaster. We report here that its sequence bears no similarity to the known DNA or protein sequences. This and act5C transcripts are loaded on different polyribosomal classes. Gel retardation experiments performed with this fragment and several others from act5C reveal no DNA binding activity. The 0.45-kb transcript, initially isolated from different developmental stages of D. melanogaster embryogenesis, is also expressed in Drosophila Kc tissue culture cells, which will be used in transformation experiments designed to identify regulatory features of the nested gene and its possible interaction at some level with its "host" act5C gene.