Fig. 3. Expression of Rpn10e mRNA is developmentally regulated. (A) PCR-based expression analysis with cDNA libraries. Degenerate PCR primers were designed for the conserved sequence motifs of S5a: ²¹⁸LALRVS²²³ and ³³⁶QSVLEN³⁴¹. PCR was performed using the cDNA libraries as templates. Note that the ∼520 bp (Rpn10e) and ∼870 bp (Rpn10c) bands were amplified only from the embryonic stem cell (ES) and embryonic brain cDNA libraries. (B) Expression of Rpn10a and Rpn10e mRNAs in embryonic, fetal and adult brains. Semi-quantitative RT–PCR (left panel) was performed using the primer pair used in (A). Southern blot analysis of PCR products (right panel) was carried out using an Rpn10e-specific cDNA probe. The sources of the mRNAs were as follows: E, day 13 mouse embryo; F, human fetal brain; A, mouse and human adult brains. (C) Northern blot analysis of Rpn10a and Rpn10e mRNAs during mouse embryonic development. Numbers above the panels stand for days post coitum (d.p.c.).