Fig. 1.
Membrane organization and biochemical characteristics of raft sub-types in murine sperm. A schematic diagram of murine sperm shows the high degree of cell polarization and compartmentalization of the plasma membrane (A). The plasma membrane overlying the acrosome (APM) is highly enriched in GM1, detected by FITC-CTB (B). Sterols and caveolin-1 are also segregated into the same area (C and D, [12, 14]). Biochemical analysis of membrane raft fractions demonstrated the presence of 3 different raft sub-types (fx 1-4, 5 and 6, and 7) characterized by reproducibly distinct lipid and protein compositions [summarized in panel E; “+” signs denote relative molar ratios (sterols or GM1 versus phospholipid) or mass ratios (total protein:total lipid) in the sub-types [9]].