Ascidian Sperm Glycosylphosphatidylinositol-anchored CRISP-like Protein as a Binding Partner for an Allorecognizable Sperm Receptor on the Vitelline Coat

Although ascidians are hermaphroditic, many species including Halocynthia roretzi are self-sterile. We previously reported that a vitelline coat polymorphic protein HrVC70, consisting of 12 EGF (epidermal growth factor)-like repeats, is a candidate allorecognition protein in H. roretzi, because the...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of biological chemistry 2008-08, Vol.283 (31), p.21725-21733
Main Authors: Urayama, Satoshi, Harada, Yoshito, Nakagawa, Yoko, Ban, Susumu, Akasaka, Mari, Kawasaki, Nana, Sawada, Hitoshi
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Detergents - pharmacology
Fertilization
Glycosylphosphatidylinositols - chemistry
Male
Membrane Glycoproteins - chemistry
Models, Biological
Molecular Sequence Data
Protein Binding
Protein Structure, Tertiary
Sequence Homology, Amino Acid
Spermatozoa - metabolism
Urochordata
Vitelline Membrane - metabolism
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Although ascidians are hermaphroditic, many species including Halocynthia roretzi are self-sterile. We previously reported that a vitelline coat polymorphic protein HrVC70, consisting of 12 EGF (epidermal growth factor)-like repeats, is a candidate allorecognition protein in H. roretzi, because the isolated HrVC70 shows higher affinity to nonself-sperm than to self-sperm. Here, we show that a sperm 35-kDa glycosylphosphatidylinositol-anchored CRISP (cysteine-rich secretory protein)-like protein HrUrabin in a low density detergent-insoluble membrane fraction is a physiological binding partner for HrVC70. We found that HrVC70 specifically interacts with HrUrabin, which had been separated by SDS-PAGE and transferred onto a nitrocellulose membrane. HrUrabin has an N-linked sugar chain, essential for binding to HrVC70. HrUrabin mRNA is expressed in the testis but not in the ovary, and the protein appears to be localized on the surface of sperm head and tail. Anti-HrUrabin antibody, which neutralizes the interaction between HrUrabin and HrVC70, potently inhibited fertilization and allorecognizable sperm-binding to HrVC70-agarose. However, no significant difference in the binding ability of HrUrabin to HrVC70 was observed in autologous and allogeneic combinations by Far Western analyses. These results indicate that sperm-egg binding in H. roretzi is mediated by the molecular interaction between HrUrabin on the sperm surface and HrVC70 on the vitelline coat, but that HrUrabin per se is unlikely to be a direct allorecognition protein.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M802631200