FIG 3

Identification of an ESE in the regulation of nt 929^3434 splicing of HPV18 pre-mRNAs. (A to C) Mapping of an ESE in regulation of in vitro splicing of HPV18 RNAs. HPV18 pre-mRNAs with successive truncations of the RNA 3′ end (A) were ³²P labeled and incubated with HeLa nuclear extract at 30°C for the indicated times (B and C). The splicing products were resolved on a 6% denaturing PAGE gel. The identities of unspliced pre-mRNAs (a) and spliced products (b, b′, c, d, and e) on the splicing gels are indicated. (D and E) Enhancement of dsx pre-mRNA splicing by the identified HPV18 ESE. dsx pre-mRNAs 1 to 7 with a fragmented ESE ∼30 nt in size from the HPV18 nt 3520 to 3635 region at their 3′ ends (D) were evaluated for their in vitro splicing activities (E). (AAG)₈ and a Py3 element (4) served as positive and negative controls, respectively. Details are shown in panels B and C.