Figure 5.

Analysis of the xlProminin-1 alternatively spliced isoforms in four tissues: the retina, brain, testis, and kidney. We found that profiles of the xlProminin-1 alternative splicing are different in these tissues. A: Products of reverse-transcription PCR (RT–PCR) from a region of extensive alternative splicing on the xlProminin-1 gene (exon 20 to 28) were separated on a 1% agarose gel and visualized with ethidium bromide staining. Five discrete PCR products were excised from the gel, cloned, and sequenced. Their exon compositions were determined and each product was designated with a Greek letter (α, β, γ, δ, and ε) for identification when used in the quantitative analysis shown in panel B. The predominant isoforms of xlProminin-1 expressed in the retina lack the alternatively spliced exons 26b, 27, and 28a, whereas the predominant isoform of xlProminin-1 expressed in the kidney retains these exons. The predominant isoforms of xlProminin-1 expressed in the brain and kidney retain exon 28a. Exon 27 was retained only when exon 26b was retained as well. B: Quantification of the xlProminin-1 alternatively spliced isoforms in four tissues: the retina, brain, testis, and kidney. The resolved RT–PCR products were linearly scanned and the optical densities were plotted. Green arrows indicate peaks that represent isoforms resulting from alternative splicing. The major isoform of xlProminin-1 expressed in the retina, ε, lacks the alternatively spliced exons 26b, 27, and 28a, whereas the major form of xlProminin-1 expressed in the kidney, α, retains all possible exons. The majority of xlProminin-1 expressed in the brain and kidney retains exon 28a.