A peptide that mimics the carboxy‐terminal domain of SNAP‐25 blocks Ca²⁺‐dependent exocytosis in chromaffin cells

Direct Visualization by Confocal Fluorescent Microscopy of the Permeation of Myristoylated Peptides Through the Cell Membrane

“…Initially these studies were intended to characterize protein-protein interactions in the exocytotic mechanism in permeabilized cells because the synthetic peptides were not able to cross the barrier of the cellular membrane. These studies demonstrated the specific interaction of syntaxin and other proteins in the fusion complex through specific domains (1,3).…”

SNAP‐25 is present on chromaffin granules and acts as a SNAP receptor

“…SNARE hypothesis predicts that the docking of vesicles with target membranes is mediated by the specific interaction between t-and v-SNAREs [7]. Although the involvement of NSF-SNAPs-SNAREs in various fusion events including exocytosis in chromaffin cells [17][18][19][20], recent studies revealed that t-SNAREs are localized not only on the plasma membrane but also on synaptic vesicles [21][22][23]. These results raised the question of whether or not syntaxin 1 and SNAP-25 act as t-SNAREs.…”

A Peptide That Mimics the C-terminal Sequence of SNAP-25 Inhibits Secretory Vesicle Docking in Chromaffin Cells

“…Recently, synthetic peptides that mimic the amino acid se-quence of segments from synaptotagmin (22,23), SNAPs (24), synaptobrevin (25) and SNAP-25 (26,27) were shown to be specific inhibitors of neurosecretion. These peptides, for which the term ESUP was coined to highlight their activity (26), are useful pharmacological tools to probe the functional role of distinct protein components in the secretory machinery, to dissect the contribution of specific domains in the proteinprotein interactions that mediate the process and to identify steps in the exocytotic cascade. The use of this new set of reagents, however, remains limited because the mechanism underlying their inhibitory activity is unkonwn.…”

“…We find that ESUP-A arrests Ca 2ϩ -dependent secretion from permeabilized chromaffin cells by inhibiting vesicle docking. (26). Cleaved peptides were purified by reversephase HPLC with a VydaC C-18 semipreparative column.…”