RRC ID 49207
Author Fukuda M, Imai A, Nashida T, Shimomura H.
Title Slp4-a/granuphilin-a interacts with syntaxin-2/3 in a Munc18-2-dependent manner.
Journal J Biol Chem
Abstract Slp4-a/granuphilin-a was originally described as a protein specifically associated with insulin-containing granules in pancreatic beta-cells, but it was subsequently found to be present on amylase-containing granules in parotid acinar cells. Although Slp4-a has been suggested to control insulin secretion through interaction with syntaxin-1a and/or Munc18-1, nothing is known about the binding partner(s) of Slp4-a during amylase release from parotid acinar cells, which do not endogenously express either syntaxin-1a or Munc18-1. In this study we systematically investigated the interaction between syntaxin-1-5 and Munc18-1-3 by co-immunoprecipitation assay using COS-7 cells and discovered that Slp4-a interacts with a closed conformation of syntaxin-2/3 in a Munc18-2-dependent manner, whereas Munc18-2 itself hardly interacts with Slp4-a at all. By contrast, Slp4-a was found to strongly interact with Munc18-1 regardless of the presence of syntaxin-2/3, and syntaxin-2/3 co-immunoprecipitated with Slp4-a only in the presence of Munc18-1/2. Deletion analysis showed that the syntaxin-2/3 (or Munc18-1/2)-binding site is a linker domain of Slp4-a (amino acid residues 144-354), a previously uncharacterized region located between the N-terminal Rab27A binding domain and the C2A domain. We also found that the Slp4-a.syntaxin-2 complex is actually present in rat parotid glands and that introduction of the antibody against Slp4-a linker domain into streptolysin O-permeabilized parotid acinar cells severely attenuates isoproterenol-stimulated amylase release, possibly by disrupting the interaction between Slp4-a and syntaxin-2/3 (or Munc18-2). These results suggest that Slp4-a modulates amylase release from parotid acinar cells through interaction with syntaxin-2/3 on the apical plasma membrane.
Volume 280(47)
Pages 39175-84
Published 2005-11-25
DOI 10.1074/jbc.M505759200
PII S0021-9258(20)59123-0
PMID 16186111
MeSH Amylases / metabolism Animals Binding Sites / genetics COS Cells Chlorocebus aethiops In Vitro Techniques Mice Multiprotein Complexes Munc18 Proteins / chemistry Munc18 Proteins / genetics Munc18 Proteins / metabolism* Mutagenesis, Site-Directed Parotid Gland / metabolism Qa-SNARE Proteins / chemistry Qa-SNARE Proteins / genetics Qa-SNARE Proteins / metabolism* Rats Recombinant Proteins / chemistry Recombinant Proteins / genetics Recombinant Proteins / metabolism Syntaxin 1 / chemistry Syntaxin 1 / genetics Syntaxin 1 / metabolism* Vesicular Transport Proteins / chemistry Vesicular Transport Proteins / genetics Vesicular Transport Proteins / metabolism*
IF 4.238
Times Cited 41
DNA material pEF-FLAG-mouse syntaxin-2 (RDB15167) pEF-FLAG-mouse syntaxin-3 (RDB15168) pEF-FLAG-mouse syntaxin-4 (RDB15169) pEF-FLAG-mouse syntaxin-5 (RDB15170) pEF-FLAG-mouse VAMP-3 (RDB15172) pEF-FLAG-mouse VAMP-8 (RDB15174) pEF-FLAG-mouse SNAP-23 (RDB15175).