Coma Membrane: Lipid Rafts

Decent Essays
Lipid rafts are defined as the subdomains of the plasma membrane that exist as distinct liquid-ordered regions of the membrane [1]. These membrane domains preferentially arise due to the interaction of specific lipids. They are mobile, dynamic and insoluble in non-ionic detergents such as Triton X-100 [2]. Lipid rafts are enriched in cholesterol, sphingolipids and phospholipids within cell membranes (Figure 1).
Figure 1. Organization of lipid rafts (Note the higher concentration of cholesterol and sphingolipids) within the raft region. (Image: WikiBooks Structural Biochemistry/Lipids/Lipid Rafts).
Sphingomyelin (SM) (also called ceramide phosphocholine), a type of sphingolipid, is a ubiquitous component of the animal membrane [3].The major sources of sphingomyelin are the bovine brain, egg yolk and milk [4]. It is, being analogous of phosphatidylcholine, typically consists of a ceramide unit with a phosphocholine moiety attached to position 1. A typical example of sphingomyelin is a d18:1/16:0 molecular species:
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These lipid rafts have been proposed to serve many functions in cell signalling, membrane trafficking and signal transduction [7]. There are some special types of proteins (e.g., transmembrane proteins and GPI-anchored proteins) that can anchor on the nanodomains to play an important role in transporting chemicals through the membrane [8]. Sphingomyelin rich rafts act as hotspots or platforms to enable transmembrane proteins to aggregate so that they can promote cell signalling events
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