Figure 4.

Confirmation of tight RPG co-expression across a wide range of conditions and cell types. (A) Base 2 logarithms of transcript levels (horizontal axis) are shown in arbitrary but normalized units from 28,032 Affymetrix microarrays from the Genevestigator Database (30). Transcripts are over hundredfold more abundant in cRPGs than in mRPGs and also vary between families of RPGs. (B) Pearson correlation coefficients (R) for cRPG transcript levels for each RPG pair indicate that variations in transcript levels are reproducible and tightly correlated. The high median correlation of 0.7875 for all cRPGs is very likely due to co-regulation. High co-expression is in accordance with the earlier observation that only a small proportion of RP molecules are located outside the ribosome and the nucleolus (39).