Protein-protein interactions: Methods, databases, and applications in virus-host study

Table 2 List of popular protein-protein interaction databases with total numbers of interactions and last updated time

PPI database	URL	Total interactions	Last updated	Ref.
STRING	http://string-db.org/	> 2000 mio	2020	Szklarczyk et al[50]
BioGrid	http://thebiogrid.org/	1746922	2021	Oughtred et al[47]
HPIDB	https://hpidb.igbb.msstate.edu/index.html	69787	2019	Ammari et al[51]
MINT	https://mint.bio.uniroma2.it/	131695	2012	Zahiri et al[3] and Licata et al[55]
DIP	https://dip.doe-mbi.ucla.edu/dip/Main.cgi	81923	2017	Zahiri et al[3] and Salwinski et al[56]
IntAct	http://www.ebi.ac.uk/intact/	1130596	2020	Orchard et al[52]
HPRD	http://www.hprd.org/	41327	2010	Zahiri et al[3] and Keshava Prasad et al[57]

PPI: Protein-protein interaction; URL: Uniform resource locator.