Related Experiment Video
Updated: Aug 27, 2025
05:44
Medium-throughput Screening Assays for Assessment of Effects on Ca2+-Signaling and Acrosome Reaction in Human Sperm
Published on: March 1, 2019
8.2K
Human sperm TMEM95 binds eggs and facilitates membrane fusion
Shaogeng Tang1,2, Yonggang Lu3,4, Will M Skinner5
1Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305.
Summary
Transmembrane protein 95 (TMEM95) on sperm interacts with egg receptors, facilitating membrane fusion essential for fertilization. This interaction, mediated by a conserved charged region on TMEM95, is crucial for successful fertilization.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Cell Biology
Background:
- Transmembrane protein 95 (TMEM95) is a sperm acrosomal membrane protein.
- TMEM95 knockout in mice causes male-specific sterility, with sperm unable to fuse with eggs.
- The precise role of TMEM95 in sperm-egg membrane fusion remains unclear.
Purpose of the Study:
- To investigate the function of human TMEM95 in sperm-egg interactions.
- To identify the egg-binding domain and potential egg receptor for TMEM95.
- To elucidate the mechanism by which TMEM95 facilitates fertilization.
Main Methods:
- Sperm penetration assays using human sperm and hamster eggs.
- X-ray crystallography to determine the structure of TMEM95.
- Site-directed mutagenesis to alter specific amino acids in TMEM95.
- Monoclonal antibody production and functional assays.
Main Results:
- Human TMEM95 binds to hamster egg membranes, indicating an egg receptor.
- A conserved, positively charged region on TMEM95 is identified as the putative receptor-binding surface.
- Mutations in this region abolish TMEM95's egg-binding activity.
- Monoclonal antibodies against TMEM95 inhibit sperm-egg fusion but not sperm-egg binding.
Conclusions:
- Sperm TMEM95 engages in a specific, receptor-mediated interaction with eggs.
- This TMEM95-egg interaction is critical for facilitating membrane fusion during fertilization.
- TMEM95 represents a potential target for novel male contraceptive strategies.
Related Concept Videos
01:38Fertilization
71.6K
During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm...
71.6K
01:43SNAREs and Membrane Fusion
11.0K
Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
11.0K
01:41Spermatogenesis
103.0K
Spermatogenesis is the process by which haploid sperm cells are produced in the male testes. It starts with stem cells located close to the outer rim of seminiferous tubules. These spermatogonial stem cells divide asymmetrically to give rise to additional stem cells (meaning that these structures “self-renew”), as well as sperm progenitors, called spermatocytes. Importantly, this method of asymmetric mitotic division maintains a population of spermatogonial stem cells in the male...
103.0K
01:26Fusion of Secretory Vesicles with the Plasma Membrane
11.2K
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
11.2K
01:15Sperm Transport
1.2K
The journey of sperm from its origin to the point of ejaculation begins within the seminiferous tubules of the testis. Here, Sertoli cells produce fluid that propels non-motile sperm through a series of conduits, starting with the straight tubules leading to the rete testis. This interconnected network of tubules acts as the initial pathway for sperm, guiding them into the efferent ductules and then into the epididymis for maturation.
The maturation phase occurs in the epididymis, where sperm...
The maturation phase occurs in the epididymis, where sperm...
1.2K