Paul M Wassarman, PhD
img_Paul M Wassarman
PROFESSOR | Cell, Developmental & Regenerative Biology
Research Topics
Developmental Biology, Protein Structure/Function, Proteomics, Reproductive Biology
Multi-Disciplinary Training Area
Cancer Biology [CAB], Development Regeneration and Stem Cells [DRS]
Molecular Mechanisms of Mammalian Fertilization

For all animals, maintenance of life and speciation depend on the process of fertilization. Fusion of eggs and sperm to form a zygote is the culmination of a complex series of interactions between two highly specialized gametes. In mammals, interactions between gametes begin when free-swimming sperm reach the site of ovulated eggs in the oviduct and then bind to eggs.

Our research focuses on mammalian egg and sperm surface components that account for species-specific binding of sperm to eggs during fertilization. For example, one of these components is a glycoprotein, called ZP3, that is present in the ovulated egg extracellular coat, or zona pellucida (ZP). ZP3 serves as a receptor for sperm during fertilization. We discovered and characterized ZP3 biochemically and, subsequently, cloned and characterized the gene encoding ZP3. While much of our research has been carried out with mice, ZP3 is present in the ZP of all mammalian eggs, including human eggs, and a ZP3-like glycoprotein is present in the extracellular coat (vitelline envelope) of eggs from amphibians, birds, fish, and many invertebrates.

Our studies have revealed that ZP3 is synthesized, processed, and secreted by oocytes, the precursors of eggs, during the growth phase of oogenesis. During growth of the oocyte, ZP3 and two other glycoproteins, called ZP1 and ZP2, assemble into an extensive network of interconnected filaments that constitute the ZP. The filaments consist of ZP2 and ZP3, present every 150 Å, and are interconnected by ZP1. Free-swimming sperm recognize and bind to specific oligosaccharides present on ZP3 at its sperm combining-site. Binding to ZP3 activates the signal transduction pathway of sperm that culminates in exocytosis, the acrosome reaction, and enables bound sperm to penetrate the ZP. Therefore, ZP3 is a structural glycoprotein, a species-specific sperm receptor, and an activator of signal transduction when sperm bind to unfertilized eggs.

All ZP glycoproteins share a large region of polypeptide (approximately 260 amino acids), called the "ZP domain". A ZP domain is also present in a wide variety of other proteins of diverse origins and functions. For example, ZP domain containing proteins are components of the mammalian egg, inner ear, nose, and kidney, as well as the Drosophila cuticle, wing epithelium, and mechanosensory organ. Our research strongly suggests that the ZP domain is a conserved module used for polymerization of extracellular proteins. Since the domain is found in a number of proteins involved in human pathologies, we are also investigating relationships between mutations in the ZP domain and disease.

In our research, we use a wide variety of contemporary methodology, including transfection of mammalian cells, exon swapping, site-directed mutagenesis, transgenesis, and targeted gene disruption. Overall, the object of our research is to understand the molecular basis of the multiple functions of ZP glycoproteins during mammalian oogenesis, fertilization, and preimplantation development and to understand the role of the ZP domain in normal and diseased states.

For more information, please visit the Wassarman Laboratory website.

PhD, Brandeis University, Graduate Dept. Biochemistry

Medical Research Council, Laboratory of Molecular Biology

Harvard Medical School, Dept. Biological Chemistry


Rockefeller Foundation Special Research Fellow

Harvard Medical School


Helen Hay Whitney Postdoctoral Fellow

Medical Research Council, Laboratory of Molecular Biology

Physicians and scientists on the faculty of the Icahn School of Medicine at Mount Sinai often interact with pharmaceutical, device and biotechnology companies to improve patient care, develop new therapies and achieve scientific breakthroughs. In order to promote an ethical and transparent environment for conducting research, providing clinical care and teaching, Mount Sinai requires that salaried faculty inform the School of their relationships with such companies.

Dr. Wassarman did not report having any of the following types of financial relationships with industry during 2022 and/or 2023: consulting, scientific advisory board, industry-sponsored lectures, service on Board of Directors, participation on industry-sponsored committees, equity ownership valued at greater than 5% of a publicly traded company or any value in a privately held company. Please note that this information may differ from information posted on corporate sites due to timing or classification differences.

Mount Sinai's faculty policies relating to faculty collaboration with industry are posted on our website. Patients may wish to ask their physician about the activities they perform for companies.