Figure 4. REST/NRSF, and neuron-specific alternatively-spliced REST4 are produced in lenses; identification of functional NRSE binding activity in the lens. A: Immunoblot and IP detection of REST and REST4 in the lens. Left panels: mAb anti-REST and anti-REST4 3121. Right panels: Immunoblot of lens proteins immunoprecipitated with NH₂-terminal anti-REST mAb, probed with mAb anti-REST or anti-REST4 3122. B: Detection of REST in lenses using anti-COOH-terminus REST. C: Amplified REST4 (R4A, R4B) and REST (RA) transcripts from lenses. D: Gel mobility shift assay identifying REST:NRSE DNA binding activity in lens extracts. NRSE and nucleotide-substituted NRSE sequences are shown below. Asterisk indicates mobility shifted complexes. NRSE and nucleotide substituted competitor were added at 25- and 100-fold excess.