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. Author manuscript; available in PMC: 2021 Feb 1.
Published in final edited form as: Trends Endocrinol Metab. 2019 Oct 19;31(2):107–117. doi: 10.1016/j.tem.2019.09.006

Figure 1. Ghrelin is activated for biological signaling by ghrelin O-acyltransferase (GOAT).

Figure 1.

Following expression in endocrine cells, ghrelin undergoes processing including serine octanoylation by GOAT (orange tail) prior to secretion into the bloodstream. In circulation, esterases can remove the octanoyl group to produce unacylated ghrelin (UAG). When reaching a cell expressing the GHS-R1a receptor, acylated ghrelin can bind and activate downstream signaling. In some cell types, plasma membrane-exposed GOAT has been proposed to catalyze re-acylation of UAG to generate ghrelin which can then activate GHS-R1a signaling.