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].