Figure 6. PTB (PTBP1) is expressed in progenitor epithelial cell and neuronal nPTB (PTBP2) in post-mitotic lens fiber cells. A: Immunoblot detection of PTB and nPTB in mouse and rat lens and brain tissue. PTB-NT: anti-NH₂-terminus PTB, PTB-CT: anti-COOH-terminus PTB, and anti-nPTB. B: Left: Amplified PTB and nPTB transcripts from lens and brain. Right: Region from amplified DNA sequence product identifying in frame exon junctions in lens. C: Immunofluorescence detection of PTB and nPTB in the lens. D: anti-nPTB (100×), E: anti-PTB-NT (100×), F: anti-PTB-CT (100×), G: DAPI nuclear stain/no 1o control (200×), H: anti-nPTB (200×), I: overlay panel G and H. J: For comparison PTB is detected in cell nuclei in rat skin, K: anti-nPTB detects little or no protein in rat skin, L: Detection of PTB in cell nuclei in epithelial cells on the anterior lens surface.