TABLE 1.

HIV-1 coreceptor and SDF-1α binding and signaling activities of CXCR4 mutants^a

CXCR4 domain	CXCR4 mutant	HIV-1 coreceptor activity	SDF-1α binding activity (nM)b	SDF-1α signaling activity	CXCR4 expression level (%)c
	293	NA	NA	−	10.0 ± 0.6d
	WT	+++	2.2 ± 1.4	+++	100
TM1	Y45A	−	1.0 ± 0.1	+++	139.6 ± 5.8
TM2	H79A	+	1.6 ± 0.1	+++	121.9 ± 5.2
	F87A	++	NAe	NAf	107.0 ± 4.5
	D97A	−	2.1 ± 1.1	+++	223.5 ± 7.6
	D97E	+	5.4 ± 1.2	+++	103.9 ± 6.7
TM3	Y121A	+++	2.3 ± 0.04	+++	87.5 ± 6.7
TM4	W161A	++	12.5 ± 3.6	+++	259.0 ± 10.8
	P163A	+	8.6 ± 0.8	+++	112.4 ± 7.3
	D171A	−	NAe	NAf	123.1 ± 8.0
TM5	Y219A	++	4.7 ± 1.3	+++	87.3 ± 6.7
TM6	W252A	+	4.6 ± 0.7	+++	84.6 ± 3.5
	Y255A	−	7.9 ± 0.05	+++	64 ± 2.9
	Y256A	+++	3.7 ± 0.9	+++	174.2 ± 8.0
	D262A	++	4.4 ± 0.2	+++	137.9 ± 5.8
	D262E	+	4.2 ± 1.5	+++	177 ± 7.4
TM7	E288A	−	4.4 ± 1.4	+/++	101.2 ± 6.5
	E288D	+	5.9 ± 0.7	+/++	127.5 ± 5.8
	F292A	++	NAe	NAf	63.3 ± 2.9
	H294A	+	2.8 ± 0.8	+++	112.7 ± 4.7
	N298A	+	1.3 ± 0.1	+++	139.7 ± 6.4
	Y302A	+++	11.5 ± 0.3	+++	141.7 ± 6.5
ECL2	D182A	+	3.4 ± 1.5	+++	98.2 ± 21.8g
	D187A	−	4.7 ± 2.1	+++	111.9 ± 23.1
	F189A	−	8.0 ± 2.1	+++	98.5 ± 23.3
	P191A	+	2.5 ± 0.4	+++	114.2 ± 26.0

^aActivities that are similar to those of wild-type CXCR4 are denoted “+++,” whereas “++,” “+,” and “−” indicate varying degrees of reduction, as follows: ++, 10 to 30% reduction; +, 30 to 60% reduction; and −, 60 to 100% reduction. Data are means ± standard deviations. NA, not available.

^bThe binding activity of each CXCR4 mutant was determined by its 50% inhibitory concentration.

^cMean fluorescence intensity (± standard deviation) for cells expressing mutant CXCR4 relative to cells expressing wild-type CXCR4.

^dNegative control.

^eThe competition binding curve did not reach a plateau of nonspecific binding.

^fCa²⁺ mobilization assays were not performed on these mutants.

^gThe expression level was determined with another CXCR4 MAb, 44708.111.