Table 1. Human, Mouse, and Rat EP3 splice variants, organized based on unique C-terminal sequence and arranged with their species homologs.
The C-terminus of these splice variants appears to impact on G protein coupling, constitutive activity, and desensitization to agonist. The G proteins with the most evidence for coupling are shown in Bold. Within each set of homologs (shown in grey or white shading), receptor properties are consistent, with the exception of the constitutive activity of Hs Var 4 and Hs Var 5.
| Species | Variant | Unique C-terminal Sequence | G-prot. coupling |
Ref. | Constitutive activity |
Ref. | De- sensitized? |
Ref. |
|---|---|---|---|---|---|---|---|---|
| Hs | Var 4 |
IRYHTNNYASSSTSLPCQCSSTLMW SDHLER |
Gi, Gq, Gβγ |
(3, 25– 27) |
None (Gi) | (28) | ||
| Mm | alpha |
IRDHTNYASSSTS_LPCPGSSALMWS DQLER |
Gi, G12, Gβγ |
(29–31) | Partial (Gi) Full (G12) |
(29, 32) |
Yes-Slow & persistent |
(33) |
| Rn | A |
IRDHTNYASSSTS_LPCPGSSVLMWS DQLER |
Gi | (34) | Full (Gi) | (34) | Yes | (35) |
| Hs | Var 5 |
VANAVSSCSNDGQKGQPISLSNEIIQ TEA |
Gi, Gs, Gq, Gβγ |
(3, 25, 26, 36) |
None (Gi) | (28) | Yes-Slow & persistent |
(36) |
| Mm | gamma |
VANAVSSCSSDGQKGQAISLSNEVVQ PGP |
Gi, Gs, Gβγ |
(30, 33, 37) |
Full (Gi), None (Gs) |
(38) | ||
| Rn | B |
VANAVSSCSSDQQKGQIASLSNEVVH PGP |
||||||
| Hs | Var 6 | MRKRRLREQEEFWGN |
Gi, Gq, Gs |
(3, 25, 26, 36) |
Partial (Gi) | (28) | Yes-Rapid & transient |
(36) |
| Hs | Var 7 | EEFWGN |
Gi, Gq, Gβγ |
(3, 25, 26, 36) |
Full (Gi) | (28) | Yes-Rapid & transient |
(36) |
| Hs | Var 8 |
MRKRRLREQLICSLQNSQIQRATAHC GQVQTYRVLNREEMEVLVSSINVYTR ISTVKTE |
Gi | (3, 26) | ||||
| Mm | Beta | MMNNLKWTFIAVPVSLGLRISSPREG |
Gi, Gβγ, G12 |
(29–31) | None (Gi), None (G12) |
(29, 32) | None | (33) |
| Rn | Beta | MMNNLKRSFIAIPASLSMRISSPREG | None | (35) | ||||
| Rn | D | FSLCFNR |