Fig. 2. Binding of factors present in Chionodraco rastrospinosus cardiac muscle nuclear extracts to myoglobin (Mb) promoter sequences. (A) 2 pmol of labeled Chaenocephalus aceratus upstream promoter sequence (-715 to -674) containing the TATAAA duplication shown in Fig. 1A were incubated with either 2 ng HeLa transcription factor IID (TFIID) (lane 1) or 5 µg of a C. rastrospinosus cardiac muscle nuclear extract (lanes 3-6) prepared as described under Materials and methods. No retardation bands were evident in the absence of added protein (lane 2). 200 pmol of unlabeled conserved TATAAAA oligo (TATAAAA, lane 5), C. aceratus upstream promoter oligo (Ace, lane 4) or C. rastrospinosus upstream oligo (Ras, lane 6) were used as competitor oligonucleotides as indicated. DNA/nuclear protein complexes were then resolved by electrophoresis and autoradiography as described under Materials and methods. (B) 2 pmol of labeled conserved TATAAAA element oligonucleotides (³²P-TATAAAA) shown in Fig. 1A were incubated with 5 µg of a C. rastrospinosus cardiac muscle nuclear extract prepared as described under Materials and methods. Retardation bands generated by incubation of the ³²P-labeled conserved TATAAAA sequence with nuclear extracts from C. aceratus are shown in lane 1. 200 pmol of unlabeled conserved TATAAAA oligo (TATAAAA, lane 2), C. aceratus upstream promoter oligonucleotide (Ace, lane 3) or C. rastrospinosus upstream oligonucleotide (Ras, lane 4) were used as competitor oligonucleotides as indicated. DNA/nuclear protein complexes were then resolved by electrophoresis and autoradiography as described under Materials and methods. Arrows denote DNA/protein complexes that are eliminated by 200 pmol of unlabeled C. aceratus upstream promoter oligonucleotide.