Table 1. Summary PBs, type of modification, modification site and the recognition motifs.

	Protein precursors	Function	Modification	Recognition motif
Native proteins	Lysozyme	Enzyme	None	Arg128
	Cytochrome c	Enzyme		Lys4 and Lys100
	Protamine	Nuclear protein		Positively charged surface amino acids
	(Strept)avidin	Tetrameric biotin-binding protein		Binding pockets of protein
	Concanavalin A, lectin A, soybean agglutinin	Tetrameric carbohydrate-binding protein		Binding pockets of protein
	Ferritin	Protein cage for iron storage		Surface charges
	Cowpea chlorotic mottle virus (CCMV)	Virus capsid		Surface charges
	Stable protein one (SP1)	Stress responsive protein		Positively charged surface amino acids and central cavity in protein
Chemically modified proteins	Human serum albumin	Blood plasma protein	Cys34	Biotin
	Somatostatin	Hormone	Cys3–Cys14	Biotin
	Insulin	Hormone	LysB29	Bipyridine
	Catalase	Hemeprotein	Lysine modification (statistical)	ssDNA (multiple)
Recombinant engineered proteins	Cytochrome b562	Hemeprotein	63Cys	Heme binding pocket
	Myoglobin	Hemeprotein	125Cys	Heme binding pocket
	C3 from Clostridium botulinum	Toxin enzyme	N-Terminal Cys	Biotin
	Cytochrome cb562	Hemeprotein	59Cys mutation at i and i + 4 positions: His59/63; His 73/77	1,10-Phenantroline histidine
	Alkaline phosphatase	Enzyme	N- or C-termini mutation	Biotin
	Split luciferase fragments	Enzyme fragments	N- or C-termini mutation	Phe-Gly-Gly
	Cyan or yellow fluorescent proteins (CFP, YFP)	Fluorescent protein	N- or C-termini mutation	Phe-Gly-Gly
	LiDPS protein cage	Ferritin protein cage	Cysteine mutation	Biotin
	Glutathione transferase dimer	Enzyme	N-Terminal polyhistidine	Polyhistidine
			N-Terminal	Phe-Gly-Gly
			137Cys	Phe-Gly-Gly
			137Cys, 138Cys	Histidine
	Chaperonin GroEL	Tetradecameric molecular chaperones	313Cys, 314Cys	Spiropyran