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CAPS primes vesicles for regulated exocytosis through SNARE protein interactions
Author(s) -
Daily Neil,
Martin Thomas
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.762.10
Subject(s) - munc 18 , exocytosis , lipid bilayer fusion , snare complex , microbiology and biotechnology , vesicle , vesicle fusion , liposome , chemistry , syntaxin , secretion , stx1a , kiss and run fusion , snap25 , membrane protein , biology , biochemistry , synaptic vesicle , membrane
CAPS (Ca 2+ ‐dependent activator protein for secretion) is a 1289 amino acid protein expressed in neural and peptide hormone‐secreting endocrine cells that functions to prime vesicles for Ca 2+ ‐triggered membrane fusion. The ability of CAPS to prime vesicles for Ca 2+ ‐triggered fusion may be through interactions with the SNARE proteins, the core components of the membrane fusion machinery. These studies utilized membrane‐reconstituted SNARE proteins to determine the SNARE protein interactions responsible for CAPS activity. There are two SNARE proteins located on the plasma membrane; syntaxin‐1A and SNAP‐25; and one on the vesicle membrane; VAMP‐2. Liposome co‐flotation studies revealed that CAPS binds with high affinity to liposomes containing syntaxin‐1A and SNAP‐25, and moderate affinity to liposomes containing VAMP‐2. In addition, CAPS interacts with the central SNARE motifs of the SNARE proteins, which it utilizes to accelerate SNARE‐dependent liposome fusion. These studies further our understanding of how CAPS interacts with the SNARE proteins and their critical role in CAPS function in regulated exocytosis.