The enigmatic sperm proteins in mammalian fertilization: an overview

• Published in: Biology of reproduction Vol. 103; no. 6; pp. 1171 - 1185
• Main Authors: Gahlay, Gagandeep Kaur, Rajput, Neha
• Format: Journal Article
• Language: English
• Published: United States Society for the Study of Reproduction 01.12.2020; Oxford University Press
• Subjects: fertilization; Oral contraceptives; Plasma; Proteins; receptor; REVIEW; Sperm; Spermatozoa; zona pellucida; sperm; receptor; zona pellucida; fertilization
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1093/biolre/ioaa140

Mammalian fertilization involves a physical interaction between a sperm and an egg followed by molecular interactions amongst their various cell surface molecules. These interactions are initially mediated on the egg's outermost matrix, zona pellucida (ZP), and then its plasma membrane. To better understand this process, it is pertinent to find the corresponding molecules on sperm that interact with ZP or the egg's plasma membrane. Although currently, we have some knowledge about the binding partners for egg's plasma membrane on sperm, yet the ones involved in an interaction with ZP have remained remarkably elusive. This review provides comprehensive knowledge about the various sperm proteins participating in mammalian fertilization and discusses the possible reasons for not being able to identify the strong sperm surface candidate (s) for ZP adhesion. It also hypothesizes the existence of a multi-protein complex(s), members of which participate in oviduct transport, cumulus penetration, zona adhesion, and adhesion/fusion with the egg's plasma membrane; with some protein(s) having multiple roles during this process. Identification of these proteins is crucial as it improves our understanding of the process and allows us to successfully treat infertility, develop contraceptives, and improve artificial reproductive technologies. Summary sentence This review comprehensively discusses the current status of various sperm proteins involved in mammalian fertilization, the reasons for failing to identify the ones involved in zona adhesion and, new perspectives to identify them.