Table III. Summary of epitope mapping data using FcγRIIa mutants
Residue NumberaBinding Activity
Receptor Construct90113130134–1381621638.7IV.3X63-21HAGG
FcγRIIa-LR WTWWQHLDPTLF++++++
FcγRIIa-HR WT...R . . . . ..++++ND
FcγRIIb WT..KRS . . N..++++++
FcγRIIa-LR W90AA... . . . ...++++ND+
FcγRIIa-LR W90A,W113AAA.. . . . ...++ND±
FcγRIIa-LR Q130K..K. . . . ...++++ND++
FcγRIIa-LR L135S.... S . . ...++++
FcγRIIa-HR L135S...RS . . ...++++++
FcγRIIa-HR T138N.... . . . N..++++ND++
FcγRIIa-HR L135S, T138N.... S . . N..++++++
FcγRIIa-HR L162N, F163V.... . . . .NV±++ND+
  • a “.” indicates residues that are unaltered from the wild-type sequence of FcγRIIa-LR, FcγRIIa-HR, or FcγRIIb.

    Residue W113 is essential to the 8.7 epitope. Residues L135 and R134-S135 are essential to the IV.3 and X63-21/7.2 epitopes in FcγRIIa and FcγRIIb, respectively.

  • ++, maximal binding equivalent to WT FcγRIIa; +, intermediate binding ; ±, weak detectable binding; −, undetectable binding over background, as exemplified in Fig. 4 and Supplemental Fig. 3; ND, no data.