QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhu, G.-Z. Articles by Primakoff, P. Search for Related Content PubMed PubMed Citation Articles by Zhu, G.-Z. Articles by Primakoff, P.

Residues SFQ (173-175) in the large extracellular loop of CD9 are required for gamete fusion

¹ Department of Cell Biology and Human Anatomy, School of Medicine, University of California Davis, Davis, CA 95616, USA
² Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
³ Institut National de la Sante et de la Récherche Medicale (INSERM), Unite 268, Hôpital Paul-Brousse, 94800 Villejuif, France
⁴ Howard Hughes Medical Institute, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

*Author for correspondence (e-mail: gzhu{at}ucdavis.edu)

Accepted 15 January 2002

Gamete fusion is the fundamental first step initiating development of a new organism. Female mice with a gene knockout for the tetraspanin CD9 (CD9 KO mice) produce mature eggs that cannot fuse with sperm. However, nothing is known about how egg surface CD9 functions in the membrane fusion process. We found that constructs including CD9’s large extracellular loop significantly inhibited gamete fusion when incubated with eggs but not when incubated with sperm, suggesting that CD9 acts by interaction with other proteins in the egg membrane. We also found that injecting developing CD9 KO oocytes with CD9 mRNA restored fusion competence to the resulting CD9 KO eggs. Injecting mRNA for either mouse CD9 or human CD9, whose large extracellular loops differ in 18 residues, rescued fusion ability of the injected CD9 KO eggs. However, when the injected mouse CD9 mRNA contained a point mutation (F174 to A) the gamete fusion level was reduced fourfold, and a change of three residues (173-175, SFQ to AAA) abolished CD9’s activity in gamete fusion. These results suggest that SFQ in the CD9 large extracellular loop may be an active site which associates with and regulates the egg fusion machinery.

Key words: Gamete fusion, CD9, Tetraspanin, mRNA injection, Mutation, Mouse

This article has been cited by other articles:

				P. Talbot, B. D. Shur, and D. G. Myles Cell Adhesion and Fertilization: Steps in Oocyte Transport, Sperm-Zona Pellucida Interactions, and Sperm-Egg Fusion Biol Reprod, January 1, 2003; 68(1): 1 - 9. [Abstract] [Full Text] [PDF]

				P. Primakoff and D. G. Myles Penetration, Adhesion, and Fusion in Mammalian Sperm-Egg Interaction Science, June 21, 2002; 296(5576): 2183 - 2185. [Abstract] [Full Text] [PDF]