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Plasma Membrane Bound ${Ca}^{2+}$-ATPase Activity in Bull Sperm

Vijayasarathy, S and Shivaji, S and Balaram, P (1980) Plasma Membrane Bound ${Ca}^{2+}$-ATPase Activity in Bull Sperm. In: FEBS Letters, 114 (1). pp. 45-47.


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The acrosome reaction in vertebrate sperm has been shown to be essential for fertilisation [1]. The process involves fusion and vesiculation of sperm head plasma membranes and the underlying outer acrosomal membrane, resulting in the exocytotic release of acrosomal enzymes. Yanagamachi and Usui have demonstrated that sperm have an absolute requirement for ${Ca}^{2+}$ during the acrosome reaction [2]. A net uptake of ${Ca}^{2+}$ has been identified [3] and experiments with the ${Ca}^{2+}$ ionophore A23187 suggest that ${Ca}^{2+}$ transmembrane fluxes govern the induction of the acrosome reaction [4]. On the basis of electron microscopic observations Gordon has suggested that an ATPase, which is not stimulated by ${Ca}^{2+}$, transports ${Ca}^{2+}$ into the periacrosomal space and a ${Ca}^{2+}$ dependent ATPase located on the outer acrosomal membrane transport this ${Ca}^{2+}$ into the acrosome, thus playing a crucial role in the induction of the acrosome reaction [ 5,6]. However, this hypothesis has been challenged by reports of the absence of ${Ca}^{2+}$-ATPase activity in guinea pig sperm [2], though earlier reports identified ${Ca}^{2+}$-ATPase activity on sperm membranes by cytochemical methods [5].

Item Type: Journal Article
Publication: FEBS Letters
Publisher: Elsevier
Additional Information: Copyright for this article belongs to Elsevier Science Ltd.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 07 Apr 2005
Last Modified: 19 Sep 2010 04:18
URI: http://eprints.iisc.ac.in/id/eprint/3048

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