TABLE 1.
Summary of effect of heptad repeat mutations on structure of peptides and on surface expression levels when incorporated in full-length SV5 F protein
| Mutation | Position in heptad repeat | N-terminal peptidesa | Melting point of 6-helix bundlea (°C) | % Total transfectedb | MFIc |
|---|---|---|---|---|---|
| wt F | α-Helical | >90 | 53.8 | 212.4 | |
| I137M | a | α-Helical | Biphasic | 51.4 | 201.2 |
| L140M | d | Nonhelical | >90 | 53.7 | 220.6 |
| V154M | d | α-Helical | >90 | 38.8 | 69.8 |
| L161M | d | Nonhelical | >90 | 47.1 | 204.9 |
a
Results published by Dutch et al.(13). α-Helicity was judged by circular dichroism at 208 and 222 nm; melting point was determinined by loss of 222-nm signal.
b
Total percent cells positive for F proteins, determined by flow cytometry as described in Materials and Methods.
c
MFI, mean fluorescent intensity, determined by flow cytometry.