FIG. 3.

Primer extension analysis of the 5′-most degradation products of SRPα RNA. (A) Unlabeled, capped SRPα RNA was added to RRL-vhs (lanes vhs) or RRL control (lanes Retic), and RNA reaction products were recovered at the indicated time points (minutes). The RNA reaction products were then analyzed by primer extension with 5′-³²P-labeled oligonucleotide complementary to nt 60 to 84 of the SRPα RNA. Primer extension products were resolved on an 8% polyacrylamide sequencing gel and detected by autoradiography. Numbered arrows indicate the positions of primer extension products representing vhs-induced novel 5′ ends. Numbers to the right of lane M (marker) indicate the sizes of DNA markers in nucleotides. (B) Sequence of the extreme 5′ 84 nt of SRPα RNA. Numbered arrows above the sequence correspond to those in panel A and indicate the positions of vhs-induced cleavage at the 5′ end of SRPα RNA. The arrow under the sequence indicates the position of the oligonucleotide primer used.