Table 1.
Summary of in vitro functional properties of PTH1R mutants.
| PTH1R allele | WT | R485X | E35K | Y134S | H223R | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Disease association | NA | Eiken syndrome | Jansen Metaphyseal Chondrodysplasia | |||||||
| Surface expression | = | - | = | -- | -- | |||||
| Binding PTH | = | = | = | = | + | |||||
| Basal cAMP | = | ++ | + | = | ++ | |||||
| Agonist responsiveness | PTH | PTHrP | PTH | PTHrP | PTH | PTHrP | PTH | PTHrP | PTH | PTHrP |
| cAMP potency | = | = | = | + | = | = | = | = | - | - |
| cAMP Emax | = | = | = | - | = | +* | = | = | - | - |
| cAMP duration | = | = | = | + | = | - | = | - | - | - |
| cAMP desensitization | = | = | = | = | = | - | = | - | ND | ND |
| iCa++, Fura2AM | = | = | + | + | = | = | - | - | - | - |
| βarrestin2yfp endosome recruitment (microscopy) | = | = | -- | -- | - | -- | = | -- | - | ND |
| βarrestin2 PM recruitment (BRET, CAAXGFP) | = | = | - | ND | = | -- | = | -- | - | ND |
| βarrestin2 endosome recruitment (BRET, FYVEGFP) | = | = | -- | ND | = | -- | = | -- | - | ND |
Presented are the functional properties of mutant PTH receptors, relative to PTH1R-WT, as assessed in HEK-293-derived cells and the data reported in the figures and tables. Symbols indicate effects relative to that of PTH1R-WT with “=” indicating the response at PTH1R-WT or a comparable response at a PTH1R mutant; “-” or “--” indicating a response that was moderately or strongly diminished, respectively, and “+” or “++” indicating a response that was moderately or strongly enhanced. PTH and PTHrP indicate responses to PTH(1-34) and PTHrP(1-36) peptides, respectively. The “*” indicates the cAMP response of PTH1R-E35K to PTHrP was increased at the ~1–3 nM doses (Fig. 3b). No βarrestin2 recruitment to endosomes in response to PTHrP(1–36) was detected for the R485X, E35K, and Y134S mutants by fluorescence microscopy (Figs. 5 and 6, and Supplemental Figs. 5 and 7). Binding PTH refers to the IC50 of PTH(1-34) for inhibiting the binding of 125I-LA-PTH (Fig. 4c). cAMP desensitization refers to the capacity to mediate a blunted response to a rechallenge with PTHrP(1–36) (Fig. 7b).
NA not applicable, ND not determined.