Project Summary (Abstract): We are applying for a supplement fund to purchase a BioComp gradient primer for fractionating density gradients. This equipment is essential for the success of the parent award as several proposed experiments, including polysome profiling, ribosome profiling, and Translating Ribosome Affinity Purification (TRAP), rely on this equipment to receive consistent and reproducible results. We desperately need this equipment to continue our investigation following equipment malfunction of our current system that cannot be repaired (system age and non-availability of parts). Additionally, no other laboratory at our institution has similar equipment we could share. Our talented undergraduate and graduate students will use this equipment to address an exciting but disputed question: does the functional specialization of ribosomes exist to support selective translation? We focus on two paralogs of predicted large ribosomal subunit 27 (Rpl27) found in fission yeast. Although these paralogs have 90% amino acid similarity and are highly conserved through much of eukaryotic evolution, their mutants demonstrate distinct phenotypes. Our preliminary data suggest that they might be part of heterogeneous ribosomes that regulate the translation of different mRNA transcripts. Dissecting the functional differences between Rpl27 paralogs may provide valuable insight into how ribosome protein paralogs potentially play a role in the heterogeneity of ribosomes, inducing a conformational change that ultimately results in altered activity and preference of mRNA transcripts accessible for translation.