Table 1.

Receptors, coreceptors, and cofactors involved in SARS-CoV-2 entry

Molecule	Category	Functional annotation	Refs
ACE2	Receptor	The major entry receptor	[2,19]
AXL	Receptor	A potential alternative receptor independent of ACE2	[59]
KREMEN1	Receptor	A potential alternative receptor independent of ACE2	[60]
ASGL1	Receptor	A potential alternative receptor independent of ACE2	[60]
CD147	Receptor	A potential alternative receptor independent of ACE2	[80]
Heparan sulfate	Coreceptor	Auxiliary attachment receptor, dependent on ACE2	[62]
Sialic acid	Coreceptor	Auxiliary attachment receptor, dependent on ACE2	[65,66]
Lectin receptors	Coreceptor	Auxiliary attachment receptor, dependent on ACE2	[64]
Neuropilin 1	Coreceptor	Auxiliary attachment receptor, dependent on ACE2	[70,71]
CD4	Coreceptor	Potential auxiliary attachment receptor, dependent on ACE2	[81]
SR-B1/ cholesterol	Cofactor	The S protein binds to cholesterol, and SR-B1 increases virion endocytosis by promoting cholesterol uptake	[75]
Furin	Cofactor	Proteolysis of S protein at the S1/S2 site	[17,25,45,53]
PC-1	Cofactor	Proteolysis of S protein at the S1/S2 site	[52,53]
Trypsin	Cofactor	Proteolysis of S protein at the S1/S2 site	[52., 53., 54.]
Matriptase	Cofactor	Proteolysis of S protein at the S1/S2 site	[52., 53., 54.]
Cathepsins	Cofactor	Proteolysis of S protein at the S1/S2 and S2′ sites	[45,54]
TMPRSS2	Cofactor	Proteolysis of S protein at the S2′ site	[25]