Table 1.

Transduction of NIH 3T3 cells by virions bearing mutant Mo-MuLV envelope proteins

Mutant envelope protein	Virus titer (TU/ml)
W606A	1.03  ± 0.03  × 105
W606G	6.52  ± 0.32  × 104
W606E	8.4  ± 2.7  × 103
W606S	3.14  ± 0.58  × 104
W606I	5.11  ± 0.71  × 104
W606F	4.68  ± 0.52  × 104
F607A	1.04  ± 0.09  × 105
F607G	9.77  ± 0.61  × 104
F607V	<3
F607W	1.05  ± 0.06  × 105
F607Y	1.04  ± 0.04  × 105
G616A	6.95  ± 0.70  × 104
G616V	4.84  ± 1.14  × 104
G616P	7.65  ± 0.79  × 104
P617A	<3
P617G	<3
P617V	0.7  ± 1.2  × 102
Cells not expressing an envelope protein	<3
Cells expressing the wild-type envelope protein	1.00  × 105

gpGFP cells were transiently transfected with the plasmids encoding the various mutant envelope proteins. After 40 h the supernatant medium was removed and used for infection of the NIH 3T3 cells. Cells that were infected express GFP and were detected by flow cytometry. Virus titer is given as transducing units per ml (TU/ml).