Figure 3. Expression and alternative splicing of pre-mRNAs of Arabidopsis SR genes in different organs is altered in the sr45-1 plants.

Expression levels were analyzed by RT-PCR with primers specific to each SR gene. Sequences of forward and reverse primers used are shown in Table S3. An equal amount of template in each reaction was verified by amplifying a constitutively expressed cyclophilin. The name of the SR gene is shown on the left of each panel. DNA sizes are indicated on the right. Isoform number is indicated on the left side of the gel. R, root; S, stem; L, leaf and I, inflorescence. Schematic diagrams in the bottom panel for each gene show the gene structure and its alternatively spliced mRNA isoforms (Numbers below each isoform indicate the number of nucleotides). Predicted proteins from splice variants are shown to the right of each isoform. Exons are filled rectangles and introns are thin lines. Black rectangles represent constitutively spliced exons whereas the red rectangles indicate the included regions in splice variants. Vertical arrowhead and ‘*’ show start and stop codons, respectively; Horizontal green and red arrowheads above and below gene structures indicate the position of forward and reverse primers, respectively. In the schematics of predicted proteins, numbers to the right are the number of amino acids in the protein. RRM, RNA recognition motif, RS, Arginine/Serine-rich domain. Blue rectangle indicates a stretch of amino acids that are not present in functional SR proteins.