TY - JOUR
T1 - Synaptic proteins and SNARE complexes are localized in lipid rafts from rat brain synaptosomes
AU - Gil, Carles
AU - Soler-Jover, Alex
AU - Blasi, Juan
AU - Aguilera, José
PY - 2005/4/1
Y1 - 2005/4/1
N2 - The biochemical characterization of the SNARE proteins present in lipid microdomains, also known as "lipid rafts," has been addressed in earlier studies, with conflicting data from different laboratories. In this study, we use rat brain synaptosomes as a model with which to examine the presence of proteins involved in exocytosis in detergent-resistant membranes (DRM), also known as 'lipid rafts.' By means of buoyancy analysis in sucrose gradients of Triton X-100-solubilized synaptosomes, we identified a pool of SNARE proteins (SNAP 25, syntaxin 1, and synaptobrevin2/VAMP2) significantly associated with DRM. Furthermore, Munc18, synaptophysin, and high amounts of the isoforms I and II of synaptotagmin were also found in DRM. In addition, SDS-resistant and temperature-dependent SNARE complexes were also detected in DRM. Treatment of synaptosomes with methyl-β-cyclodextrin resulted in persistence of the proteins present in the DRM isolated using Triton X-100, whilst strongly impairing calcium-dependent glutamate release. The results from the present work show that lipid microdomains are sites where SNARE proteins and complexes are actually present, as well as important elements in the control of regulated exocytosis. © 2005 Elsevier Inc. All rights reserved.
AB - The biochemical characterization of the SNARE proteins present in lipid microdomains, also known as "lipid rafts," has been addressed in earlier studies, with conflicting data from different laboratories. In this study, we use rat brain synaptosomes as a model with which to examine the presence of proteins involved in exocytosis in detergent-resistant membranes (DRM), also known as 'lipid rafts.' By means of buoyancy analysis in sucrose gradients of Triton X-100-solubilized synaptosomes, we identified a pool of SNARE proteins (SNAP 25, syntaxin 1, and synaptobrevin2/VAMP2) significantly associated with DRM. Furthermore, Munc18, synaptophysin, and high amounts of the isoforms I and II of synaptotagmin were also found in DRM. In addition, SDS-resistant and temperature-dependent SNARE complexes were also detected in DRM. Treatment of synaptosomes with methyl-β-cyclodextrin resulted in persistence of the proteins present in the DRM isolated using Triton X-100, whilst strongly impairing calcium-dependent glutamate release. The results from the present work show that lipid microdomains are sites where SNARE proteins and complexes are actually present, as well as important elements in the control of regulated exocytosis. © 2005 Elsevier Inc. All rights reserved.
KW - Exocytosis
KW - Lipid rafts
KW - Membrane microdomains
KW - SNARE proteins
KW - Synaptic vesicles
U2 - 10.1016/j.bbrc.2005.01.111
DO - 10.1016/j.bbrc.2005.01.111
M3 - Article
SN - 0006-291X
VL - 329
SP - 117
EP - 124
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -