Segregation of micron‐scale membrane sub‐domains in live murine sperm

• DOI: 10.1002/jcp.20504
• Publication Date: 2005-10-12T22:16:49Z
• Authors: Vimal Selvaraj; Atsushi Asano; Danielle E. Buttke; John L. McElwee; Jacquelyn L. Nelson; Collin A. Wolff; Tanya Merdiushev; Miguel W. Fornés; Alex W. Cohen; Michael P. Lisanti; George H. Rothblat; Gregory S. Kopf; Alexander J. Travis
• Keywords: Lipid raft; Capacitation; Acrosome reaction; Filipin

Abstract Lipid rafts, membrane sub‐domains enriched in sterols and sphingolipids, are controversial because demonstrations of rafts have often utilized fixed cells. We showed living sperm that the ganglioside G M1 localized to a micron‐scale sub‐domain plasma overlying acrosome. investigated four models proposed for maintenance. segregation was maintained live incubated under non‐capacitating conditions, after sterol efflux, alteration necessary capacitation. The complete lack diffusion post‐acrosomal (PAPM) cells argued against transient confinement zone model. However, within seconds cessation motility, dramatically redistributed several microns from acrosomal post‐acrosomal, non‐raft sub‐domain. This redistribution not accompanied by movement sterols, induced pentameric cholera toxin subunit B (CTB). These data lipid–lipid interaction model Although impossible rule out lipid shell definitively, mice lacking caveolin‐1 both , arguing role shells surrounding Scanning electron microscopy freeze‐dried without fixation identified cytoskeletal structures at boundary. drugs used disrupt actin intermediate filaments had no effect on we found disulfide‐bonded proteins played significant segregation. Together, these provide an example extreme terms size stability segregation, implicate protein‐based compartmentation mechanism. © 2005 Wiley‐Liss, Inc.