TABLE 1

Summary of mutant resultsa

MutantSurface expressionFusionConformationTriggerabilityImmunoblot detection (whole-cell lysate)
Alanine mutants
    WT++++Pre-F trimer++
    I64A++−−Pre-F trimer+(+)
    K65A++−−Pre-F trimer−−
    K66A+++−−Pre-F trimer−−
    K68A+++−−Pre-F trimer−−
    D73A+Pre-F, trimer and monomer mixtureNP
    K75A+++−−Pre-F trimer++
Charge-conserving mutants
    K65R++(+)+++Pre-F trimer
    K66R++(+)+++Pre-F trimer
    K68R−−NPNP
    D73E−−NPNP
    K75R+++Pre-F trimer
Oppositely charged mutants
    K65E+++−−Pre-F trimer
    K66E+−−Post-F
    K68E+++−−Pre-F trimer
    D73R+Post-F
    K75E++−−Post-F
Uncharged length-conserving mutants
    K65Q+++−−Pre-F trimer
    K66Q+++−−Pre-F trimer
    K68Q+++−−Pre-F trimer
    D73N++++Pre-F, trimer and monomer mixture
    K75Q+(+)−−Pre-F, Post-F, trimer, monomer mixture
Additional mutants
    I64GNo
    I64LNo
    I64VLow
  • a +, each symbol represents approximately 50%; (+), 25%; −, deficient compared to the WT, with each symbol approximating 50%; NP, not performed (protein not detected in immunoblots).