Table 2.

gp120 binding activity of rCD4, CD4M3, and its mutants

Competitor	IC50†, M
sCD4	1.4  ±  0.1  ×  10−9
CD4M3	4.0  ±  0.5  ×  10−5
Lys16Ala	2.0  ±  0.1  ×  10−5
Gly18Val	7.5  ±  0.5  ×  10−5
Gln20Ala	7.5  ±  0.6  ×  10−6
Gly21Val	>1  ×  10−3
Ser22Ala	1.0  ±  0.5  ×  10−4
Phe23Ala	>1  ×  10−3
Thr25Ala	8.5  ±  0.9  ×  10−6
Gly27Val	3.5  ±  0.2  ×  10−5

Mutants of mini-CD4 are indicated by the residue mutation. 

^† Concentration (±SD) of competitor required for 50% inhibition of gp120 binding to coated rCD4 in competitive ELISA.