Role of Egg Sulfolipidimmobilizing Protein 1 on Mouse Sperm-Egg Plasma Membrane Binding

• Published in: Biology of reproduction 1999-09, Vol.61 (3), p.749-756
• Main Authors: AHNONKITPANIT, V, WHITE, D, SUWAJANAKORN, S, KAN, F. W. K, NAMKING, M, WELLS, G, KAMOLVARIN, N, TANPHAICHITR, N
• Format: Article
• Language: English
• Subjects: Animals; Antibodies - pharmacology; Biological and medical sciences; Carrier Proteins - analysis; Carrier Proteins - antagonists & inhibitors; Carrier Proteins - physiology; Cell Membrane - chemistry; Cell Membrane - metabolism; Female; Fluorescent Antibody Technique, Direct; Fundamental and applied biological sciences. Psychology; Immunoblotting; Male; Mammalian female genital system; Mice; Microscopy, Immunoelectron; Morphology. Physiology; Ovum - chemistry; Ovum - physiology; Ovum - ultrastructure; Sperm-Ovum Interactions; Spermatozoa - physiology; Spermatozoa - ultrastructure; Vertebrates: reproduction
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod61.3.749

We have shown that sperm sulfolipidimmobilizing protein 1 (SLIP1, molecular mass of 68 kDa), a sulfogalactosylglycerolipid (SGG)-binding protein, is significant in sperm-zona pellucida (ZP) interaction. The objective of this study was to localize SLIP1 on the egg and determine its role in gamete interaction. Immunofluorescence and immunoprotein A gold electron microscopy localized SLIP1 to the egg plasma membrane. In vitro gamete binding, using zona-free eggs preincubated with antiSLIP1 Fab before coincubation with sperm, showed a significant, dose-dependent decrease in sperm-egg plasma membrane binding. Similar results were obtained when affinity-purified antiSLIP1 IgG was used for egg pretreatment. The significance of egg SLIP1 in sperm-egg plasma membrane binding was further demonstrated by a decrease (36–52%) in in vitro fertilization when zona-intact eggs were pretreated with antiSLIP1 IgG. Since SLIP1 has been shown to bind SGG in vitro, we investigated the possibility that sperm SGG may participate in sperm-egg plasma membrane binding through egg SLIP1. Pretreatment of sperm with antiSGG Fab prior to coincubation with zona-free eggs resulted in a dose-dependent decrease in sperm-egg plasma membrane binding. Collectively, these findings strongly suggest a role for egg SLIP1 in sperm-egg plasma membrane interaction, which may be through its binding to sperm SGG.