TABLE 2.

Characterization of fusion peptide mutants

Peptidea	Cell surface expression	Processing	Oligomer (trimer)	Receptor binding	SU* production		Infectivityb	Env viral incorporation	Fusion
					−Tva	+Tva
wt	+	+	+	+	−	+	3.3 × 105	+	+
Mutants	+					+
Position 1
Glu	+	+	+	+	−	+	2.3 × 104	+	−
Lys	+	+	+	+	−	+	1.8 × 103	+	−
Position 2
Glu	+	+	+	+	−	+	2.5 × 103	+	−
Lys	+	+	+	+	−	+	9.0 × 102	+	−
Position 3
Glu	+	+/−	+	+	+	+	2.2 × 102	+	−
Lys	+	+/−	+	+	+	+	7.5 × 100	+	−

^aPositions 1, 2, and 3 are underlined, in that order, in the sequence I F A S I L A P G V A A A Q A L R E I E R L. 

^bExpressed as infectious units per milliliter of viral stock.