Week In Science

A remarkable paper titled Functional Specificity among Ribosomal Proteins Regulates Gene Expression (Cell, Vol 131, 557-571, 02 November 2007) authored by Suzanne Komili, Natalie G. Farny, Frederick P. Roth, and Pamela A. Silver indicates that there may be a ribosomal code complementing the already recognized genetic and histone codes. Together they would form a triad of codes corresponding to three critical biomolecular functions: information storage, transcription and translation. The best known of the three explains how the identity and sequence of amino acids found in proteins is coded in DNA. The histone code, found in eukaryotic organisms, involves the regulation of the transcription process. A ribosomal code is relevant to the translation of genetic information stored in mRNA codons to the protein synthesis process through the correct sequencing of amino acids.

The Cell paper notes the duplication of genes encoding ribosomal proteins in Saccharomyces cerevisiae. Also noted are assembly and localization differential requirements exhibited by ribosomal protein paralogs. Ribosomal proteins are subjected to post translational modification affecting function. The authors state their data indicates that specific cellular processes involve specialization of ribosomal proteins. This in turn supports the existence of a ribosomal code.

Histone chaperones: an escort network regulating histone traffic which appears in Nature Structural & Molecular Biology - 14, 997 - 1007 (2007) and is authored by Leanne De Koning, Armelle Corpet, James E Haber and Geneviève Almouzni, discusses histone chaperones which play a vital role in enabling gene expression. Chaperones are proteins that help ensure the proper folding of other proteins. Histones are the main protein component of chromatin. As the authors state: "The multiplicity of histone chaperone partners, including histone modifiers, nucleosome remodelers and cell-cycle regulators, is relevant to their coordination with key cellular processes. Given the current interest in chromatin as a source of epigenetic marks, we address the potential contributions of histone chaperones to epigenetic memory and genome stability."