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Abstract We present the Codon Statistics Database, an online database that contains codon usage statistics for all the species with reference or representative genomes in RefSeq (over 15,000). The user can search for any species and access two sets of tables. One set lists, for each codon, the frequency, the Relative Synonymous Codon Usage, and whether the codon is preferred. Another set of tables lists, for each gene, its GC content, Effective Number of Codons, Codon Adaptation Index, and frequency of optimal codons. Equivalent tables can be accessed for (1) all nuclear genes, (2) nuclear genes encoding ribosomal proteins, (3) mitochondrial genes, and (4) chloroplast genes (if available in the relevant assembly). The user can also search for any taxonomic group (e.g., “primates”) and obtain a table comparing all the species in the group. The database is free to access without registration at http://codonstatsdb.unr.edu. 

Abstract The different proteins of any proteome evolve at enormously different rates. One of the primary factors influencing rates of protein evolution is expression level, with highly expressed proteins tending to evolve at slow rates. This phenomenon, known as the expression level–evolutionary rate (E–R) anticorrelation, has been attributed to the abundance‐dependent deleterious effects of misfolding or misinteraction. We have recently shown that secreted proteins either lack an E–R anticorrelation or exhibit a significantly reduced E–R anticorrelation. This effect may be due to the strict quality control to which secreted proteins are subject in the endoplasmic reticulum (which is expected to reduce the rate of misfolding and its deleterious effects) or to their extracellular location (expected to reduce the rate of misinteraction and its deleterious effects). Among secreted proteins, N‐glycosylated ones are under particularly strong quality control. Here, we investigate how N‐linked glycosylation affects the E–R anticorrelation. Strikingly, we observe apositiveE–R correlation among N‐glycosylated proteins. That is, N‐glycoproteins that are highly expressed evolve at faster rates than lowly expressed N‐glycoproteins, in contrast to what is observed among intracellular proteins.