Figure 1.

Splicing patterns of AtPop1 mRNAs. The 3344 bp long genomic region between AUG1 and UAA2 is shown as a heavy black line; distances in bp are indicated by the ruler above the line. Start and stop codons delimiting the expressed coding regions are drawn as solid black arrows and those with unclear in vivo function as outlined arrows. The position of the conserved regions (Pop1 domain and POPLD) is depicted as heavy grey lines below the genomic region. The exons of mRNA variants 1–3 are drawn as grey boxes identified by roman numerals and connected by dotted lines indicating the length of excised introns. Variant 1 encodes a 190 amino acids protein containing the Pop1 domain; in the unspliced RNA, the ORF terminates at UAA1 after 151 residues. Variants 2a and b are combined into one drawing: 2a encodes an 826 amino acids long ORF extending from AUG1 to UAA2. In variant 2b, the alternative splicing events at the borders of exon 2 are indicated by black dots. The resulting frame shift creates a 659 residues long ORF between AUG2 and UAA2. The novel variant 3 has an extended exon 4 and encodes a 307 amino acids ORF terminating at UGA2. For accession numbers and sequence details, see text and Supplementary Figures S1 and S3.