TABLE 1.

Characterization of detected non-synonymous hIP genetic variants

Agonist binding and cAMP generation were performed with iloprost as described under “Experimental Procedures.” The variants are abbreviated as follows. The first letter represents the amino acid code for the wild-type amino acid, numbers represent amino acid position, and the last letter identifies the amino acid polymorphism. The symbol % represents conservation at the equivalent position across all prostanoid receptors (high conservation, >50%). Binding constants are given as K_i in nm, and cAMP activity is given as EC₅₀. Bold results represent mutations that have defective signaling. Their full dose response is provided in Fig 3. ND, not detectible; >50, no significant counts on competition binding despite the presence of significant protein on Western analysis.

hIP	%	Ki (nm) (n)	EC50 (nm) (n)	Bmax (pmol/mg protein) (n)
Newly characterized hIP variants
WT		7.9 ± 1.7 (9)	1.2 ± 0.1 (10)	1.1 ± 0.1 (3)
V15A	36	5.5 ± 4.1 (3)	1.7 ± 1.0 (3)	1.5 ± 0.1 (3)
L104R	100	>50 (6)a	3.5 ± 0.2 (4)b	0.7 ± 0.2 (3)
M113T	100	>50 (4)a	ND (3)a	0.3 ± 0.06 (3)c
G181A	10	11.8 ± 4.8 (3)	2.0 ± 0.9 (3)	1.1 ± 0.1 (3)
V196L	33	4.5 ± 0.6 (3)	0.6 ± 0.3 (3)	1.6 ± 0.2 (3)
R215C	64	9.4 ± 1.1 (3)	1.1 ± 0.1 (6)	0.7 ± 0.05 (3)b
P226T	10	8.0 ± 0.4 (4)	0.7 ± 0.2 (3)	1.0 ± 0.2 (4)
G231R	29	4.4 ± 1.6 (3)	0.9 ± 0.4 (3)	0.7 ± 0.2 (3)
I293N	69	>50 (3)a	1.9 ± 0.6 (3)	0.3 ± 0.05 (6)c
S319W	17	9.0 ± 1.7 (3)	0.7 ± 0.2 (4)	1.4 ± 0.2 (3)
S319L	17	8.0 ± 1.3 (3)	1.0 ± 0.2 (3)	1.4 ± 0.1 (3)
E354D	10	8.3 ± 0.7 (3)	1.1 ± 0.5 (3)	1.1 ± 0.1 (3)
S369R	10	15.7 ± 5.9 (4)	0.7 ± 0.3 (3)	0.8 ± 0.1 (4)
Previously characterized hIP variants
WT		7.9 ± 1.7 (9)	1.2 ± 0.1 (10)	1.1 ± 0.1 (3)
V25M	21	6.1 ± 2.3 (4)	0.9 ± 0.4 (3)	1.5 ± 0.4 (3)
R77C	19	6.4 ± 1.1 (3)	0.9 ± 0.3 (3)	0.3 ± 0.04 (3)c
R212C	50	4.3 ± 1.1 (7)	2.6 ± 0.7 (9)b	0.5 ± 0.03 (3)c
R212H	50	2.2 ± 1.2 (4)	2.8 ± 0.5 (5)b	0.8 ± 0.2 (3)
R279C	100	>50 (4)a	34.0 ± 3.0 (5)a	0.3 ± 0.02 (3)c

^a p < 0.001.

^b p < 0.05.

^c p < 0.01.