Sperm plasma membrane

About: Sperm plasma membrane is a research topic. Over the lifetime, 1016 publications have been published within this topic receiving 49964 citations.

Solubilization and partial purification from mouse sperm membranes of the specific binding activity for 3-quinuclidinyl benzilate, a potent inhibitor of the zona pellucida-induced acrosome reaction.

Abstract: 3-Quinuclidinyl benzilate (QNB), a potent antagonist of muscarinic acetylcholine receptors, has been demonstrated to inhibit specifically the zona pellucida (ZP)-inducud acrosome reaction (AR) in mouse sperm (Florman and Storey, 1982; Dev Biol 91:121–130). In this study we describe the solubilization and partial purification of the mouse sperm QNB binding activity which may represent a component of the putative receptor complex for ZP on the sperm plasma membrane. Sperm membranes were isolated from cell homogenates of washed, capacitated, epididymal mouse sperm. Scatchard plots of QNB binding to these membranes indicated a single class of binding sites with KD = 7.2 nM and Bmax = 8700 sites/cell. These binding characteristics are similar to those seen with QNB binding to whole cells (Florman and Storey, 1982, J Androl 3:157–164). Sperm membranes were solubilized using 1% digitonin/0.2% cholate, and the resultant detergent-soluble fraction possessed QNB binding activity similar to that of intact membranes. The detergent-soluble fraction maintained intact ZP receptor(s)–G protein coupling in that treatment of this fraction with either ZP or mastoparan resulted in a 35% or 65% increase in specific GTPγS binding, respectively. The solubilized membrane preparation was fractionated by gel permeation HPLC. A majority of specific QNB binding activity was confined to one HPLC fraction. Analysis of this fraction by SDS–PAGE revealed a complex of approximately 5 proteins unique to this fraction. The most prominent protein had a Mr of 72 kDa, which is within the Mr range for muscarinic receptors. A protein with Mr = 41 kDa was also present within this fraction. Subsequent pertussis toxin (PTX)-catalyzed ADP-ribosylation of this fraction revealed this protein to be the α subunit of the Gi class of G proteins. Although the QNB binding activity could not be positively identified, we propose that it is contained in one or more of the proteins unique to this fraction and that these proteins, including Gi, may act as part of a sperm receptor complex for the ZP. © 1994 Wiley-Liss, Inc.

Sperm Surface Proteomics

Abstract: This contribution will focus exclusively on the total (global) protein composition (the proteome) of the sperm surface. Immune responses directed towards sperm surface proteins may cause infertility since functionally intact sperm are under immune attack. The immune attack can be achieved directly by deteriorating sperm or by antibody blocking of a sperm surface protein with a specific function in the fertilization process. Antibodies that bind to the sperm surface proteins could also impair the fertilization potential of sperm more indirectly by causing lateral redistribution of the sperm surface proteins and/or by hindrance of the assemblage of functional membrane protein complexes involved in fertilization. Currently the information about the sperm plasma membrane proteome is increasing but has only led to limited understanding of the functionality that is related to the complex ordering and processing of this specific cell surface. New proteomic data and new strategies designed for complete coverage of the surface proteome of mammalian sperm will significantly increase our understanding of how fertilization is accomplished but also how immune responses may frustrate this process. This information will become highly relevant for studying immune infertility. An overview is provided about the current knowledge of the sperm surface and how this structure should experimentally be approached for proteomic studies. Comparative analysis of different mammalian species is covered as this will provide better understanding for the possibilities and limitations of analyzing the surface proteome of human sperm.

Sperm characterization of the Amazonian freshwater cururu stingray Potamotrygon wallacei (Potamotryogonidae): basic knowledge for reproduction and conservation plans.

Abstract: This study aimed to describe the morphology and sperm quality of free-living adult males of cururu stingray Potamotrygon wallacei, endemic from the Rio Negro basin, Brazilian Amazon. The sperm was collected in loco from the seminal vesicle region and fixed in buffered saline formaldehyde solution for further evaluation of morphometry, sperm plasma membrane integrity and sperm concentration. The spermatozoa presented a total length of 138.25 ± 1.82 μm with a helical shape and a long head. A high percentage of cells with intact membrane (98 ± 2%) and normal spermatozoa (92 ± 1%) were observed. The cell concentration was 0.34 ± 0.05 × 1010 spermatozoa/ml of semen. These observations are unprecedented for potamotrygonid species and will serve as a basis for future management and conservation strategies.