The biological significance of detergent-resistant membranes in spermatozoa.
As mammalian spermatozoa ascend the female reproductive tract, they acquire the ability to fertilize an oocyte via a complex cascade of biophysical and biochemical changes collectively know as 'capacitation'. In virtually all species studied, capacitation is accompanied by dramatic remodeling of the surface architecture, in order to render spermatozoa competent to recognize the oocyte and initiate fertilization. Although the fundamental mechanisms that underpin the dynamic redistribution of sperm surface proteins are poorly understood, recent evidence indicates that this process may be facilitated, at least in part, by specialized membrane microdomains or lipid rafts. This notion is consistent with numerous demonstrations that lipid rafts contain a number of putative zona pellucida receptors, undergo a marked capacitation-associated lateral migration to the apical region of the sperm head, and possess the ability to selectively bind to the zona pellucida of unfertilized, but not fertilized oocytes. Accordingly, this review aims to cover the latest insights into sperm lipid raft research and considers the evidence that these microdomains serve as platforms for the assembly of key recognition molecules on the sperm surface during capacitation.