Figure 2.

Gene transcription, alternative splicing, and post-translational modifications of ghrelin. Ghrelin is encoded by GHRL gene, which also can produce peptides other than native ghrelin through alternative splicing. Exon 3-deleted peptide lacks the exon number 3 and In1-ghrelin is product of a messenger RNA, which retains the intron-1 transcript of GHRL gene. The initial form of each peptide contains a N-terminal signal peptide that is cleaved by signal peptidase in the endoplasmic reticulum and gives rise to proghrelin, exon 3-deleted proghrelin, and pro-In1-ghrelin. By further post-translational processing, proghrelin is cleaved to produce different peptides.