Table 2.

Cell surface expression, virion incorporation, and receptor binding of proline mutantsa

MutantRelative cell surface expressionRelative virion incorporationRelative s47 saturation bindingKD for S47 binding (nM)
R0.7 ± 0.10.7 ± 0.30.9 ± 0.1ND
D0.9 ± 0.11.2 ± 0.11.2 ± 0.4ND
E0.9 ± 0.10.9 ± 0.21.0 ± 0.2ND
N0.8 ± 0.01.4 ± 0.30.9 ± 0.3ND
Q1.0 ± 0.12.1 ± 0.30.9 ± 0.1ND
S0.9 ± 0.11.01.0 ± 0.514
T0.8 ± 0.11.0 ± 0.30.8 ± 0.15
P1.01.01.017
G1.1 ± 0.10.8 ± 0.11.2 ± 0.010
A0.7 ± 0.10.8 ± 0.20.5 ± 0.07
V1.4 ± 0.11.1 ± 0.10.7 ± 0.016
L0.8 ± 0.00.40.9 ± 0.1ND
F0.7 ± 0.00.60.2 ± 0.12
Acl1.3 ± 0.21.0 ± 0.3NDND
HANDNDNDND
  • a Data were obtained and normalized to that for wild-type EnvA (P) as described in Materials and Methods. They are presented in order of increasing residue hydrophobicity. (Hydrophobicity tables from different sources rank residues differently, both in order and by extent of hydrophobic nature. We present our data in an order of increasing hydrophobicity representing the consensus ordering from the tables in reference 16, 10,34, and 17. When plotted versus hydrophobicity for each of the four individual hydrophobicity scales, a similar correlation between high infectivity and intermediate hydrophobicity was obtained [data not shown].) All values are reported as fractions of the P values ± standard error of the mean. Because values were normalized to wild type for each experiment, the error in P is embedded in the values for the other errors. Where no errors are given for relative virion incorporation (other than P), a single blot was quantitated. Otherwise, results were averaged from two to five independent experiments. ND, not determined.