A synthetic peptide of the N‐terminus of ADP‐ribosylation factor (ARF) inhibits regulated exocytosis in adrenal chromaffin cells

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Abstract
We have investigated the role of ADP‐ribosylation factor (ARF) in regulated exocytosis in digitonin‐permeabilized adrenal ehromaffin cells by the use of a synthetic peptide, hARFl(2–17), based on the N‐terminus of the protein. hARFl(2–17) inhibited Ca2+‐dependent but not basal exocytosis, whereas equimolar levels of other synthetic peptides were ineffective. The inhibitory effect of hARFl(2–17) was dose‐dependent and half‐maximal at 12 μM. GTPγS‐induced secretion in the presence of non‐stimulatory CA2+ concentrations was also inhibited by hARFl(2–17). These results point to a hitherto unsuspected role for ARF in regulated exocytosis, and the potency of the hARFl(2–17) peptide suggests that ARF is essential for exocytosis in bovine adrenal chromaffin cells.