Site | Mutation (if Performed) | Positiona | Putative Interactions, Pharmacological Role | Potency Loss (Ratio for 2-MeSADP)a |
---|---|---|---|---|
TM1 | ||||
Y58 | 1.39 | H-bond donor to S314b,c,d | N.A. | |
N69 | 1.50 | H-bond donor to S317c,d | N.A. | |
TM2 | ||||
S87 | 2.40 | H-bond acceptor from Y324c,d | N.A. | |
N92 | 2.45 | H-bond acceptor from W176c,d | N.A. | |
D97 | 2.50 | NA+ bindingc | N.A. | |
Y110 | 2.63 | Agonist effecte | N.A. | |
TM3 | ||||
R128 | A | 3.29 | Counterion to α-phosphated,f | >50,000 |
F131 | A | 3.32 | Modulatory toward agonist, but not antagonistf | 8 |
H132 | A | 3.33 | Modulatoryg | 7 |
Y136 | A | 3.37 | Modulatoryg | 6 |
S138 | 3.39 | H-bond acceptor from N316c,d | N.A. | |
H148 | 3.49 | H-bond acceptor from R255c,d | N.A. | |
TM4 | ||||
S172 | 4.46 | H-bond acceptor from N92c,d | N.A. | |
W176 | 4.50 | H-bond donor to N92c,d | N.A. | |
TM5 | ||||
T221 | A | 5.42 | Small effectf | 7 |
T222 | A | 5.43 | Proximity to γ-phosphatef | 5 |
F226 | A | 5.47 | Binding of antagonistsf | 9 |
TM6 | ||||
R255 | 6.30 | H-bond donor to H148c,dh | N.A. | |
Y273 | A | 6.48 | Receptor activationd,i | >3,000 |
F | 6.48 | Receptor activation rescuedd | 2 | |
H277 | A | 6.52 | Effect of agonist but not antagonistf | 45 |
K280 | A | 6.55 | Counterion to β-phosphate of ADP; action of PPADSd,e,j | 810 |
TM7 | ||||
Y306 | A | 7.35 | Modulatory toward agonist effects onlyd | 5 |
F | 7.35 | Modulatoryd,g | 6 | |
Q307 | A | 7.36 | H-bond acceptor from exocyclic NH of ADPd,f | 210 |
R310 | A | 7.39 | Counterion to α-phosphated,f | >50,000 |
K | 7.39 | Rescue of agonist (partial) and antagonist (full) effectsf | 190 | |
S314 | A | 7.43 | Activation, H-bond donor to adenine N1 or N3;d,f H-bond acceptor from Y58b | >50,000 |
T | 7.43 | Rescue of agonist effectf | 5 | |
N316 | 7.45 | H-bond donor to S138c,d | N.A. | |
S317 | A | 7.46 | H-bond acceptor from N69; no pharmacological effectd,f | 0.7 |
D320 | 7.49 | Receptor activationc,k | N.A. | |
Y324 | 7.53 | H-bond donor to S87c,d | N.A. | |
Extracellular and cytoplasmic regions | ||||
C42 | A | N-terminal | Disulfide with C296f | 22,000 |
T47 | N-terminal | Meta-binding sitec,f | N.A. | |
C124 | A | EL1 | Disulfide with C202 | >50,000 |
K125 | A | EL1 | No effectf | 3 |
L157 | IL2 | G protein interactionc,l | N.A. | |
R195 | A | EL2 | No effectf | 2 |
K196 | A | EL2 | No effectf | 1 |
K198 | A | EL2 | Modulatoryf | 8 |
Y203 | A | EL2 | Agonist effectsd,m | >3,000 |
F | EL2 | Rescue of agonist effectsd | 5 | |
D204 | A | EL2 | Meta-binding sitef | 30 |
N | EL2 | Unable to rescue functionf | 270 | |
E | EL2 | Unable to rescue functionf | 66 | |
D208 | A | EL2 | No effectf | 2 |
E209 | A | EL2 | Meta-binding site; H-bonding to ribosef | 7800 |
D | EL2 | H-bonding rescuedf | 1 | |
Q | EL2 | H-bonding rescuedf | 4 | |
R | EL2 | H-bonding rescuedf | 2 | |
R212 | A | EL2 | Small effectf | 4 |
R285 | A | EL3 | Small effectf | 4 |
R287 | A | EL3 | Meta-binding site; H-bonding to E209f | 6700 |
K | EL3 | Charge rescue (partial) of agonist effectsf | 34 | |
Q | EL3 | Partial rescuef | 240 | |
E | EL3 | Disrupts E209 interactionf | >50,000 | |
D289 | A | EL3 | No effectf | 2 |
C296 | A | EL3 | Disulfide with C42f | 2300 |
D300 | A | EL3 | Agonist effectsf | 45 |
R301 | A | EL3 | No effectf | 1 |
D329 | C-terminal | Beginning of H8c,d,n | N.A. | |
R333 | C-terminal | Required for Gq couplingo | N.A. | |
R334 | C-terminal | Required for Gq couplingo | N.A. | |
K341 | C-terminal | End of H8c,d,n | N.A. |
N.A. not applicable; EL extracellular loop; IL intracellular loop
↵ a Residue identifier of format X.YZ refers to the TM X and residue YZ with respect to a highly conserved amino acid in each TM numbered 50 (Ballesteros et al., 2001; Costanzi et al., 2004); potency ratio shown is EC50 at mutant receptor divided by EC50 at the wild-type; the EC50 of 2-MeSADP at the wild-type human P2Y1 receptors was reported as 2.2 ± 0.5f or 3 ± 1d nM
↵ b Applies only to ground state of receptor
↵ c Not mutated, prediction from modeling only
↵ d Costanzi et al. (2004)
↵ e Hoffmann et al. (2004)
↵ f Moro and Jacobson (2002) and references therein
↵ g Modulatory toward effects of agonist and nucleotide antagonist
↵ h Analogous to E(6.30) of the β2 adrenergic receptor involved in an `ionic lock' with R(3.50) but no electrostatic interaction with V(3.50) of the P2Y1 receptor is possible; for the P2Y1 receptor, a similarly placed interaction is predicted between R(6.30) and H(3.49)
↵ i Mutation precludes only activation by agonist, but not binding of agonist or antagonist
↵ j Guo et al. (2002)
↵ k Analogous to the N of the NPxxxY motif involved in activation of thyroid-stimulating hormone (Claeysen et al., 2002) and other receptors
↵ l Moro et al. (1993)
↵ m Mutation precludes only activation and binding of agonist, but not binding of antagonist
↵ n An eighth helical region (cytoplasmic), by analogy to rhodopsin; a putative palmitoylation site (Cys) in this region is predicted for P2Y4, P2Y12, and P2Y14, but not P2Y1 receptors
↵ o Ding et al. (2005)