SED1 function during mammalian sperm-egg adhesion.
A prerequisite for successful fertilization is the species-specific binding of sperm to the extracellular coat of the egg. Gamete binding triggers the release of sperm hydrolytic enzymes that digest a path through the egg coat, thus bringing sperm into proximity with the egg plasma membrane where gamete fusion occurs. Although some components of the sperm membrane and the egg coat that participate in sperm-egg interactions have been identified, results from targeted deletions and gene substitutions indicate that other, as yet unidentified, gamete receptors must contribute to sperm-egg binding. Recent studies implicate the bi-motif protein, SED1, as being required for successful sperm-egg adhesion in mouse. SED1 contains Notch-like EGF repeats as well as discoidin/F5/8 complement domains--motifs that mediate a variety of cell-cell and cell-matrix interactions. SED1's ability to promote gamete adhesion resides within its two discoidin/F5/8C domains, which are able to dock to substrates as diverse as phospholipid membranes and extracellular matrices. SED1 is also expressed in a wide range of tissues and epithelia, where it may function similarly as an adhesive protein facilitating cell-cell and/or cell-matrix interactions.
Shur
Barry D
BD
Department of Cell Biology, Whitehead Biomedical Research Building, Emory University School of Medicine, 615 Michael Street, Atlanta, Georgia 30322, USA. barry@cellbio.emory.edu
Ensslin
Michael A
MA
Rodeheffer
Carey
C
D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D004527:Egg Proteins / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D008297:Male; D008322:Mammals / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013084:Sperm-Ovum Interactions / Q000235:genetics / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*
D004527:Egg Proteins; D008565:Membrane Proteins; C477266:SED1 protein, mouse