Table 1.

Summary of characteristics of essential genes.

Category	Feature	Description	References
Sequence features	Expression level	Studies have shown that essential genes are expressed at higher levels than nonessential genes.	[96, 97]
	Codon bias	Essential genes are more likely to use optimal codons. Some characteristics of codons can serve as parameters for assessing the ideal codon usage, which plays a critical role in ensuring precise translation of highly expressed genes.	[98, 99]
	Protein size	Larger proteins have more biological functions and are more conserved, it is believed that larger proteins tend to be enriched in essential proteins.	[100]
	Gene position	There is a higher proportion of essential genes located in operons and the leading strand.	[101]
	Subcellular location	Essential proteins are found predominantly in the cytoplasm, although significantly greater proportions of nonessential proteins are situated in other cellular areas.	[100, 102]
	Hurst exponent	Essential genes have a lower average Hurst exponent.	[103]
Context‐related features	Evolutionary relationships	Essential genes evolve more slowly than nonessential genes.	[104, 105]
	Protein function	Essential genes are hubs of protein–protein interaction networks, which are more commonly involved in fundamental categories according to gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway.	[106, 107]
	Protein‐protein interactions	Essential genes tend to have higher connectivity in protein‐protein interaction networks.	[108, 109]
	Domain properties	Protein essentiality is to be conserved through the function of protein domains or domain combinations.	[110, 111]