Fig. 4.

Western blot analysis of transcription factors in brain. Western blot analysis was performed with some of the transcription factor “candidates” listed in Table 2. A: Cells were isolated from the brains of mice between P16 and P21 of age and sorted into O1-depleted (O1−) and O1-enriched (O1+) pools. Nuclear extracts were prepared from the sorted pools, and directly from whole brain (P21), and analyzed for expression of the indicated transcription factors. Despite every attempt to load equal amounts of protein, the immunosorted fractions contained roughly 2-fold less protein compared to nuclear extracts from whole brain as determined by Ponceau S staining of the membranes following protein transfer (data not shown), and supported by Western blot analysis for SNEV1, which appears to be constitutively expressed in nuclei. New blots were used for all analyses except SNEV1, which was first incubated with an anti-Purβ antibody, then stripped and incubated with an antibody against SNEV1. [Nuclear extract from P21 brain was not included in the analysis of MSY1]. B: Nuclear extracts were prepared from the brains of mice at the indicated ages (postnatal days) and analyzed by Western blot for expression of transcription factors. New blots were used for all analyses except SNEV1, which was first incubated with an anti-Purα antibody, then stripped and incubated with an antibody against SNEV1.