Lipid Rafts and Detergent-Resistant Membranes in Epithelial Keratinocytes
Authors
Kathleen P. McGuinn and My G. Mahoney
Institution
Thomas Jefferson Uni
Country
United States
Year
2014
Journal
Methods in Mol Biol
Abstract
Our understanding of the plasma membrane has markedly increased since Singer and Nicolson proposed
the fluid mosaic model in 1972. While their revolutionary theory of the lipid bilayer remains largely valid, it
is now known that lipids and proteins are not randomly dispersed throughout the plasma membrane but
instead may be organized within membrane microdomains, commonly referred to as lipid rafts. Lipid rafts
are highly dynamic, detergent resistant, and enriched with both cholesterol and glycosphingolipids. The
two main types are flotillin-rich planar lipid rafts and caveolin-rich caveolae. It is proposed that flotillin and
caveolin proteins regulate cell communication by compartmentalizing and interacting with signal transduction
proteins within their respective lipid microdomains. Consequently, membrane rafts play an important
role in vital cellular functions including migration, invasion, and signaling; thus, alterations in their
microenvironment can initiate signaling pathways that affect cellular function and behavior. Therefore, the
identification of lipid rafts and their associated proteins is integral to the study of transmembrane signaling.
Here, we review the current standard protocols and biochemical approaches used to isolate and define raft
proteins from epithelial cells and tissues. Furthermore, in Section 3 of this chapter, detailed protocols are
offered for isolating lipid rafts by subjection to detergent and sucrose density centrifugation, as well as
an approach for selectively isolating caveolae. Methods to manipulate rafts with treatments such as
methyl-β-cyclodextrin and flotillin III are also described.
Keywords: Lipid raft, Detergent resistant, Membrane microdomain, Caveolae, Caveolin,
Methyl-β-cyclodextrin