Table 1. JRFL gp160 loop deletion or replacement mutants.

JRFL Env loops	Original loop sequence	Replacing linker sequence and designated name of the construct
V1V2	VNATNTTNDSEGTMERGEIKNCSFNITTSIRDEVQKEYALFYKLDVVPIDNNNTSYRL	GSGSG (ΔV1V2)
V2	NITTSIRDEVQKEYALFYKLDVVPIDNNNTSYRL	GSGSG (ΔV2)
V2 crown	FYKLD	AAAAA (ΔV2C)
loop D	NFTNNAKT	AAAA (ΔlpD)
V3	NTRKSIHIGPGRAFYTTGEIIG	GSGSG (ΔV3)
V3 crown	GPGR	AAAA (ΔV3C)
CD4bl	SSGGDPEIVMH	GSGSG (ΔCD4bl)
V4	NSTQLFNSTWNNNTEGSNNTEGNTITLP	GSGSG (ΔV4); or GGGGSGGGGSGGGGSGSGSG (ΔV4fl)
V5	INENGTEIFR	GSGSG (ΔV5); or GGGGSGSGSG (ΔV5fl)

The amino acid (AA) sequences of the original loops and flexible linkers for replacement are shown. V2 and V3 crown sequences are underlined. CD4bl: CD4 binding loop. ΔV4fl and ΔV5fl: V4 and V5 loops replaced with flexible linkers of the same lengths. Designated names of resultant constructs are indicted in parentheses.