Variant transcript analysis of murine Toll interacting protein (Tollip). (a) Genomic arrangement of murine Toll interacting protein (Tollip) on the minus strand of mouse chromosome 7. TC (cap-analysis gene expression (CAGE) tag clusters) indicate two transcriptional start sites (TSSs): variants 1, 2 and 4 are from the major TSS at 129,607 K and variant 3 is from a cluster of CAGE tags (indicated by arrows) at 129,623 K. (b) The probe track indicates the exon junctions spanned by oligoprobes on the splicing array. Variant transcripts are indicated by boxed exon cartoon. Variant 1 is a 274 amino acid protein initiating from exon 1B. Variant 2 is a 220 amino acid dominant-negative protein that skips exon 6 and so lacks the carboxyl-terminal CUE domain. Variant 3 initiates from exon 1A and lacks an open reading frame (ORF). Variant 4 contains a cryptic splice acceptor in intron 3 that disrupts the ORF, resulting in a noncoding transcript. (c) Scatter plot shows the distribution of expression detected by each probe. The average signal of each probe (unstimulated bone-marrow derived macrophages (BMMs) and BMMs subjected to seven hours of stimulation with lipopolysaccharide (+7 hrs LPS); x axis) was plotted against the normalized ratio of +7 hrs LPS/unstimulated BMM (y axis). Junction probes are indicated by a triangle and exon probes are indicated by black squares. Probe 1A measured the expression of the alternate terminating exon associated with variant 2. Probes 7A and 8A measured the expression of variants 3 and 4, respectively. Probe 6A (variant 1) was significantly repressed after LPS treatment (P < 0.05).