Codon Usage Bias

Codon frequencies, GC content, tRNA adaptation index, and the genetic code
Codon Usage Bias
Synonymous codons are not used equally. High-expression genes prefer codons matching abundant tRNAs.

tRNA Adaptation Index (tAI): 0=random, 1=perfectly optimized.

GC3 = GC content at 3rd codon position — strongest bias signal.