FIG. 3.

PAP II and PAP III mRNAs are expressed in chicken DT40 cells. (A) Diagram of RNase protection assays with probe 1. The open boxes indicate sequences encoded by PAP exons. The dotted box indicates sequences encoded by intron 12, which are unique to PAP III (40). The solid lines indicate probe 1 or the protected fragments. (C) Diagram of RNase protection assays with probe 2. The solid, horizontal-striped, dotted, and slant-striped boxes indicate sequences encoded by exons 19, 20, 21, and 22, respectively (40). In both panels A and C, the expected sizes of the probes and protected fragments are indicated on the right. (B) Total RNA isolated from DT40 cells was analyzed with probe 1. (D) An RNase protection assay was performed with probe 2. In both panels B and D, the RNase protection products (lanes 2) were separated on a 5% polyacrylamide-urea gel. Labeled MspI-digested pBR322 DNA was used as a DNA size marker (nt, lane 1). The positions of probes and different forms of PAP are indicated by arrows.