CatSperβ, a Novel Transmembrane Protein in the CatSper Channel Complex*
- ‡Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 and §Howard Hughes Medical Institute, Enders 1309, Children's Hospital Boston, Boston, Massachusetts 02115
- ↵1 To whom correspondence should be addressed: Dept. of Biology, University of Pennsylvania, 415 S. University Ave. Philadelphia, PA 19104. Tel.: 215-898-9271; Fax: 215-898-8780; E-mail: dren{at}sas.upenn.edu.
Abstract
Four CatSper ion channel subunit genes (CatSpers 1-4) are required for sperm cell hyperactivation and male fertility. The four proteins assemble (presumably as a tetramer) to form a sperm-specific, alkalinization-activated Ca2+-selective channel. We set out to identify proteins associating with CatSper that might help explain its unique role in spermatozoa. Using a transgenic approach, a CatSper1 complex was purified from mouse testis that contained heat shock protein 70-2, a testis-specific chaperone, and CatSperβ, a novel protein with two putative transmembrane-spanning domains. Like the CatSper ion channel subunits, CatSperβ was restricted to testis and localized to the principal piece of the sperm tail. CatSperβ protein is absent in CatSper1-/- sperm, suggesting that it is required for trafficking or formation of a stable channel complex. CatSperβ is the first identified auxiliary protein to the CatSper channel.
- Received February 5, 2007.
- Revision received April 26, 2007.
- The American Society for Biochemistry and Molecular Biology, Inc.
