The species-specific egg receptor for sea urchin sperm adhesion is EBR1,a novel ADAMTS protein.
Species-specific adhesion of sperm to the egg during sea urchin fertilization involves the interaction of the sperm adhesive protein,bindin, and a complementary receptor on the egg surface,and serves to restrict the gene pool to individuals of the same species. We used PCR representation difference analysis to clone the species-specific egg receptor for bindin, EBR1, from Strongylocentrotus franciscanus (Sf) and S. purpuratus (Sp). Sf-EBR1 contains a novel ADAMTS-like N-terminal domain followed by approximately 19 tandem EBR repeats consisting of alternating CUB and thrombospondin type 1 (TSP-1) domains where the last 10 EBR repeats are species-specific and highly conserved. Recombinant protein corresponding to the species-specific EBR repeat displays species-specific sperm adhesion and bindin-binding activity. The Sp-EBR1 ortholog has the same ADAMTS (a disintegrin and metalloprotease with thrombospondin type-1 modules) core region followed by eight and one-half tandem egg bindin receptor (EBR) repeats that share 88% identity with the Sf-EBR1 repeats,but has an entirely different species-specific domain consisting of hyalin-like (HYR) repeats. Thus,the species-specific domains of egg bindin receptor 1 (EBR1) from both species function as the egg surface receptor to mediate species-specific sperm adhesion.
Kamei
Noriko
N
Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California 92697, USA. nkamei@uci.edu
Glabe
Charles G
CG
D000818:Animals; D005306:Fertilization / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012617:Sea Urchins / Q000201:enzymology*; D013084:Sperm-Ovum Interactions / Q000502:physiology*
D011956:Receptors, Cell Surface; C035027:egg surface sperm receptor