TY - JOUR
T1 - Stomatin is a major lipid-raft component of platelet alpha-granules
T2 - STOMATIN IN alpha-GRANULAR RAFTS
AU - Mairhofer, Mario
AU - Steiner, Marianne
AU - Mosgoeller, Wilhelm
AU - Prohaska, Rainer
AU - Salzer, Ulrich
N1 - Funding Information:
This work was supported in part by NIH Grant EY03357.
PY - 2002/8/1
Y1 - 2002/8/1
N2 - Lipid rafts are detergent-resistant, cholesterol- and sphingolipid-rich membrane domains that are involved in important cellular processes such as signal transduction and intracellular trafficking. Stomatin, a major lipid-raft component of erythrocytes and epithelial cells, is also an abundant platelet protein. Microscopical methods and subcellular fractionation showed that stomatin is located mainly at the alpha-granular membrane. The lipid-raft marker proteins flotillin-1 and flotillin-2 were also present in platelets but excluded from alpha granules. Stomatin and the flotillins were associated with Triton X-100-insoluble lipid rafts. Whereas stomatin was partly soluble in Triton X-100, it was insoluble in the detergents Lubrol and 3-[(3-cholamidopropyl)dimethylamonio]-1-propyl sulfonate (CHAPS). Flotation experiments after CHAPS lysis of platelets revealed a distinct set of lipid-raft-associated proteins, which were identified by matrix-assisted laser desorption/ionization mass spectrometry as stomatin, flotillin-1, flotillin-2, CD36, CD9, integrin alpha(IIb)beta(3), and the glucose transporter GLUT-3. Stomatin, the flotillins, and CD36 were exclusively present in this lipid-raft fraction. Activation of platelets by calcium ionophore A23187 or thrombin led to translocation of stomatin to the plasma membrane, cleavage by calpain, and specific sorting into released microvesicles. In conclusion, this study demonstrated the existence of alpha-granular lipid rafts and suggests an important role for stomatin in the organization and function of alpha granules.
AB - Lipid rafts are detergent-resistant, cholesterol- and sphingolipid-rich membrane domains that are involved in important cellular processes such as signal transduction and intracellular trafficking. Stomatin, a major lipid-raft component of erythrocytes and epithelial cells, is also an abundant platelet protein. Microscopical methods and subcellular fractionation showed that stomatin is located mainly at the alpha-granular membrane. The lipid-raft marker proteins flotillin-1 and flotillin-2 were also present in platelets but excluded from alpha granules. Stomatin and the flotillins were associated with Triton X-100-insoluble lipid rafts. Whereas stomatin was partly soluble in Triton X-100, it was insoluble in the detergents Lubrol and 3-[(3-cholamidopropyl)dimethylamonio]-1-propyl sulfonate (CHAPS). Flotation experiments after CHAPS lysis of platelets revealed a distinct set of lipid-raft-associated proteins, which were identified by matrix-assisted laser desorption/ionization mass spectrometry as stomatin, flotillin-1, flotillin-2, CD36, CD9, integrin alpha(IIb)beta(3), and the glucose transporter GLUT-3. Stomatin, the flotillins, and CD36 were exclusively present in this lipid-raft fraction. Activation of platelets by calcium ionophore A23187 or thrombin led to translocation of stomatin to the plasma membrane, cleavage by calpain, and specific sorting into released microvesicles. In conclusion, this study demonstrated the existence of alpha-granular lipid rafts and suggests an important role for stomatin in the organization and function of alpha granules.
KW - platelets
KW - lipid rafts
KW - alpha-granules
KW - detergent insolubility
KW - platelets
KW - lipid rafts
KW - alpha-granules
KW - detergent insolubility
UR - http://www.scopus.com/inward/record.url?scp=0036682475&partnerID=8YFLogxK
U2 - 10.1182/blood.V100.3.897
DO - 10.1182/blood.V100.3.897
M3 - Article
SN - 0006-4971
VL - 100
SP - 897
EP - 904
JO - Blood
JF - Blood
IS - 3
ER -