Fig. 2.

Deletion of the CACAC motif in the proximal downstream intron abolishes the ability of SRp75 to inhibit exon 10 splicing, although that deletion still binds SRp75. (A) Nucleotides +1 to +30 of the intron downstream of tau exon 10. The deletions are demarcated by bars above or below the sequence. (B) RT-PCR of wild-type and deleted SP/10L in COS cells in the absence and presence of SRp75. The RT-PCR products come from 1:1 co-transfections of tau constructs and FLAG- SRp75. Exon ratio calculations, primers, graph conventions and p-value notations are as in Fig. 1C. (C) ³²P-labeled riboprobes containing wild-type or deleted exon 10 were incubated with extracts from COS cells transfected with FLAG- SRp75 and were immunoprecipitated by anti-FLAG monoclonal antibody M2. Amounts of riboprobe bound to SRp75 were calculated by measuring the counts retained after washing (means ± SD of three analyses). The asterisks show riboprobes in which SRp75 binding is significantly different from that of the wild-type riboprobe (std); the p-value notations are as in Fig. 1C. Equal amounts of FLAG- SRp75 were present in each experiment and the counts were normalized for starting probe counts and C-content.