Causes of Codon Bias


Base composition
Genome favours one nucleotide pair
Codons ending in those appear more often
Composition bias can be due to mutation bias or other factors
Can vary across genome => Isochores
Drives multicellular codon bias?

Selection
Use of specific codons selectively advantageous
Based on tRNA populations in cell
Not necessarily for maximal translational efficiency
Drives unicellular codon bias?