Translator Disclaimer
1 January 2005 Tyrosine Phosphorylation Generates Multiple Isoforms of the Mitochondrial Capsule Protein, Phospholipid Hydroperoxide Glutathione Peroxidase (PHGPx), During Hamster Sperm Capacitation
Author Affiliations +
Abstract

Sperm capacitation is a maturation process, occurring in the female reproductive tract, that produces fertilization-competent spermatozoa. Protein tyrosine phosphorylation represents an important event in capacitation. The present study demonstrates the capacitation-dependent tyrosine-phosphorylation of phospholipid hydroperoxide glutathione peroxidase (PHGPx), the disulfide cross-linked, major structural protein of the sperm mitochondrial capsule. Immunofluorescence microscopy using an antiphosphotyrosine monoclonal antibody (anti-pY20) demonstrated the presence of capacitation-associated tyrosine phosphorylated proteins in the flagellum of hamster spermatozoa. Among the tyrosine-phosphorylated polypeptides (Mr 19 000– 99 000), a 19-kDa polypeptide was the only one that can be solubilized completely by Triton X-100-dithiothreitol (DTT). The 19-kDa polypeptide was purified by anion-exchange chromatography and by immunoaffinity chromatography. Proteomic identification of the 19-kDa polypeptide by nano-electrospray tandem mass spectrometry yielded six peptides that matched the National Center for Biotechnology Information (NCBI) database sequences of bovine PHGPx. Indirect immunofluorescence localized PHGPx to the midpiece of the flagellum and the immunoblot analysis demonstrated its DTT-dependent release from purified flagella. DTT extracts of noncapacitated spermatozoa exhibited a charge train of four major PHGPx isoforms (pIs 7.5– 9.0) by two-dimensional PAGE, whereas capacitated spermatozoa revealed the generation of new acidic PHGPx isoforms with isoelectric points ranging between pH 6.0–7.0 and 4.0–5.0, indicating that it is posttranslationally modified during capacitation. These data suggest that the tyrosine-phosphorylation of PHGPx may represent an important event in the signaling pathway(s) associated with capacitation and could potentially affect mitochondrial function.

Subir K. Nagdas, Virginia P. Winfrey, and Gary E. Olson "Tyrosine Phosphorylation Generates Multiple Isoforms of the Mitochondrial Capsule Protein, Phospholipid Hydroperoxide Glutathione Peroxidase (PHGPx), During Hamster Sperm Capacitation 1," Biology of Reproduction 72(1), (1 January 2005). https://doi.org/10.1095/biolreprod.104.033530
Received: 23 June 2004; Accepted: 1 September 2004; Published: 1 January 2005
JOURNAL ARTICLE
8 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top