Autoradiographic visualization of the mouse egg's sperm receptor bound to sperm
The extracellular coat, or zona pellucida, of mammalian eggs contains species-specific receptors to which sperm bind as a prelude to fertilization. In mice, ZP3, one of only three zona pellucida glycoproteins, serves as sperm receptor. Acrosome-intact, but not acrosome-reacted, mouse sperm recognize and interact with specific O-linked oligosaccharides of ZP3 resulting in sperm-egg binding. Binding, in turn, causes sperm to undergo the acrosome reaction; a membrane fusion event that results in loss of plasma membrane at the anterior region of the head and exposure of inner acrosomal membrane with its associated acrosomal contents. Bound, acrosome-reacted sperm are able to penetrate the zona pellucida and fuse with the egg's plasma membrane (fertilization). In the present report, we examined binding of radioiodinated, purified, egg ZP3 to both acrosome intact and acrosome reacted sperm by whole-mount autoradiography. Silver grains due to bound 125I-ZP3 were found localized to the acrosomal cap region of heads of acrosome-reacted sperm. Under the same conditions, 125I-fetuin bound at only background levels to heads of both acrosome-intact and -reacted sperm, and 125I-ZP2, another zona pellucida glycoprotein, bound preferentially to acrosome-reacted sperm. These results provide visual evidence that ZP3 binds preferentially and specifically to heads of acrosome intact sperm; properties expected of the mouse egg's sperm receptor.
- Research Organization:
- Roche Research Center, Nutley, NJ
- OSTI ID:
- 5617662
- Journal Information:
- J. Cell Biol.; (United States), Vol. 4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Human homolog of the mouse sperm receptor
A role for carbohydrate recognition in mammalian sperm-egg binding
Related Subjects
OOCYTES
AUTORADIOGRAPHY
SPERMATOZOA
RECEPTORS
CELL MEMBRANES
CHEMICAL BONDS
FERTILIZATION
GLUCOPROTEINS
IODINE 125
LABELLED COMPOUNDS
MICE
ANIMALS
BETA DECAY RADIOISOTOPES
CARBOHYDRATES
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
GAMETES
GERM CELLS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
RODENTS
SACCHARIDES
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques