Figure 1
Alternative splicing of a GPCR. ( A) The structural domains of GPCRs are annotated as N-tail (amino terminus), EC1-3 (extracellular loop domains 1–3), TM1-7 (transmembrane domains 1–7), IC1-3 (intracellular loop domains 1–3) and C-tail (carboxy terminus).( B) Generation of a 5TM mutant of the ghrelin receptor results from failure to remove the intron between the two coding exons. An alternative stop codon and a polyadenylation signal within the intron (dark box) are used to produce a C-terminal truncated GPCR form that is unable to bind to growth hormone secretagogues [14].
Table 1
GPCR splice variants with altered or deleted transmembrane domains
| Receptor | Splicing consequence | General properties of splice variant | Dom/neg? | Refs. |
|---|---|---|---|---|
| Vasopressin receptor, subtype 2 (V2) | V2b is a truncated 6TM mutant. | V2b is retained in the ER where its C-terminus can be either intracellular or extracellular. | Yes | [51] |
Figure 2
Schematic representation of the structural relationship between wild-type and truncated GPCRs.