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lipid rafts; detergent-insoluble glycolipid-rich domains (DIGs); glycolipid-enriched membranes (GEMs); low-density Triton-insoluble (LDTI) complexes

Cholesterol-rich microdomains in the exoplasmic leaflet of the membrane bilayer. Plasma membrane lipid rafts consist of clusters of about 20 proteins & ~3500 sphingolipid molecules. They are about 50 nm in diameter, but may aggregate into the um range by receptor activation or bivalent antibodies against raft- associated surface antigens. Lipid rafts may also occur in the GOLGI. Constituents: 1) lipids a) cholesterol b) sphingolipids - sphingomyelin - gangliosides (i.e. GM1) 2) proteins a) integral membrane proteins - flotillins - caveolin - stomatins - LAT/PAG - MAL/BENE - VIP36 b) glypiated proteins (exoplasmic face) - Thy-1 - alkaline phosphatase - folate receptor c) cytoplasmic face (proteins modified with alphipatic groups) - src family tyrosine kinases - G-alpha protein - endothelial NO synthase (eNOS, NOS-3) - H-ras d) scavenger receptors - CD36 - SRBI - RAGE e) tyrosine kinase receptors - EGF receptor - PDGF receptor - insulin receptor f) endothelin receptor g) neuronal lipid rafts [5] - amyloid precursor protein (APP)* - APP gamma-secretase - BACE1 * substrate (APP#) & enzymes (APP gamma-secretase & BACE1) present in neuronal lipid rafts. beta-Peptide (dimers) may accumulate in neuronal lipid rafts in mouse-model for Alzheimer's disease. apoE & phosphorylated tau found associated with the lipid rafts after appearance of beta-peptide. [5] # most APP is not within lipid rafts Function: 1) vesicular trafficking 2) signal transduction 3) compartment for APP gamma-secretase 3) formation of caveolae

Related

advanced glycosylation end product [AGE] receptor (AGER, RAGE) alkaline phosphatase CD36; platelet glycoprotein 4; platelet glycoprotein IV; GPIV; glycoprotein IIIb; GPIIIB; leukocyte differentiation antigen CD36; PAS IV; PAS-4; platelet collagen receptor; fatty acid translocase; FAT; Thrombospondin receptor (GP3B, GP4) CD90; thy-1 membrane glycoprotein; thy-1 antigen; CDw90 (THY1) cholesterol endothelin receptor epidermal growth factor receptor; receptor tyrosine-protein kinase ErbB-1 (EGFR, ERBB1, HER1) flotillin folate receptor or folate-binding protein G-protein ganglioside glypiated protein H-ras proto-oncogene protein (Harvey ras, p21Hras, Ha-ras) insulin receptor; IR; (INSR) NO synthase-3 (endothelial NO synthase, NOS3, ENOS) platelet-derived growth factor [PDGF] receptor sphingomyelin src proto-oncogene protein family

Specific

caveola

General

cellular membrane

References

  1. Galbiati et al, Cell 106:403, 2001 PMID: 11525727
  2. Simon & Toomre, Nature Reviews 1:31, 2000 PMID: 11413487
  3. Marx J. Science 294:1862, 2001
  4. Nebl T et al, JBC 277(45):43399 2002 PMID: 12202484
  5. Kawarabayashi T et al, J Neurosci 24(15):3801, 2004 PMID: 15084661