{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T11:55:01Z","timestamp":1790942101466,"version":"4.1.0"},"reference-count":44,"publisher":"Oxford University Press (OUP)","issue":"4","license":[{"start":{"date-parts":[[2012,10,1]],"date-time":"2012-10-01T00:00:00Z","timestamp":1349049600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":["rep.bioscientifica.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2012,10,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The mechanisms leading to capacitation in stallion sperm are poorly understood. The objective of our study was to define factors associated with regulation of protein tyrosine phosphorylation in stallion sperm. Stallion sperm were incubated for 4\u200ah in modified Whitten's media with or without bicarbonate, calcium, or BSA. When sperm were incubated in air at 30\u00d7106\/ml at initial pH 7.25, protein tyrosine phosphorylation was detected only in medium containing 25\u200amM bicarbonate alone; calcium and BSA inhibited phosphorylation. Surprisingly, this inhibition did not occur when sperm were incubated at 10\u00d7106\/ml. The final pH values after incubation at 30\u00d7106 and 10\u00d7106 sperm\/ml were 7.43\u00b10.04 and 7.83\u00b10.07 (mean\u00b1s.e.m.) respectively. Sperm were then incubated at initial pH values of 7.25, 7.90, or 8.50 in either air or 5% CO2. Protein tyrosine phosphorylation increased with increasing final medium pH, regardless of the addition of bicarbonate or BSA. An increase in environmental pH was observed when raw semen was instilled into the uteri of estrous mares and retrieved after 30\u200amin (from 7.47\u00b10.10 to 7.85\u00b10.08), demonstrating a potential physiological role for pH regulation of capacitation. Sperm incubated in the presence of the calmodulin (CaM) inhibitor W-7 exhibited a dose-dependent increase in protein tyrosine phosphorylation, suggesting that the inhibitory effect of calcium was CaM mediated. These results show for the first time a major regulatory role of external pH, calcium, and CaM in stallion sperm protein tyrosine phosphorylation.<\/jats:p>","DOI":"10.1530\/rep-12-0067","type":"journal-article","created":{"date-parts":[[2012,7,28]],"date-time":"2012-07-28T07:50:02Z","timestamp":1343461802000},"page":"411-422","update-policy":"https:\/\/doi.org\/10.1530\/crossmarkpolicy-1","source":"Crossref","is-referenced-by-count":42,"title":["Calcium\u2013calmodulin and pH regulate protein tyrosine phosphorylation in stallion sperm"],"prefix":"10.1093","volume":"144","author":[{"given":"L","family":"Gonz\u00e1lez-Fern\u00e1ndez","sequence":"first","affiliation":[{"name":"Departments of Veterinary, Physiology and Pharmacology, Large Animal Clinical Sciences College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4466, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B","family":"Mac\u00edas-Garc\u00eda","sequence":"additional","affiliation":[{"name":"Departments of Veterinary, Physiology and Pharmacology, Large Animal Clinical Sciences College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4466, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I C","family":"Velez","sequence":"additional","affiliation":[{"name":"Departments of Veterinary, Physiology and Pharmacology, Large Animal Clinical Sciences College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4466, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D D","family":"Varner","sequence":"additional","affiliation":[{"name":"Departments of Veterinary, Physiology and Pharmacology, Large Animal Clinical Sciences College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4466, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K","family":"Hinrichs","sequence":"additional","affiliation":[{"name":"Departments of Veterinary, Physiology and Pharmacology, Large Animal Clinical Sciences College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4466, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2012,10,1]]},"reference":[{"key":"2026010712582474200_bib1","first-page":"581","article-title":"Observations on the penetration of the sperm in the mammalian egg","volume":"4","author":"Austin","year":"1951","journal-title":"Australian Journal of Scientific Research. Ser. B: Biological Sciences"},{"key":"2026010712582474200_bib2","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1242\/jcs.00842","article-title":"Analysis of the mechanism by which calcium negatively regulates the tyrosine phosphorylation cascade associated with sperm capacitation","volume":"117","author":"Baker","year":"2004","journal-title":"Journal of Cell Science"},{"key":"2026010712582474200_bib3","doi-asserted-by":"crossref","first-page":"1239","DOI":"10.1016\/S0093-691X(03)00144-4","article-title":"Reactive oxygen species promote tyrosine phosphorylation and capacitation in equine spermatozoa","volume":"60","author":"Baumber","year":"2003","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib4","doi-asserted-by":"crossref","first-page":"1188","DOI":"10.1016\/j.theriogenology.2008.06.021","article-title":"Capacitation-dependent reorganization of microdomains in the apical sperm head plasma membrane: functional relationship with zona binding and the zona-induced acrosome reaction","volume":"70","author":"Boerke","year":"2008","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib5","doi-asserted-by":"crossref","first-page":"1111","DOI":"10.1016\/0093-691X(91)90358-K","article-title":"The effect of uterine lavage performed four hours post insemination on pregnancy rate in mares","volume":"35","author":"Brinsko","year":"1991","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib6","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1006\/dbio.1996.0301","article-title":"Regulation of protein tyrosine phosphorylation in human sperm by a calcium\/calmodulin-dependent mechanism: identification of A kinase anchor proteins as major substrates for tyrosine phosphorylation","volume":"180","author":"Carrera","year":"1996","journal-title":"Developmental Biology"},{"key":"2026010712582474200_bib7","first-page":"219","article-title":"Calmodulin level changes associated with cyclic AMP treatment in cultured squirrel monkey oocytes and sperm","volume":"2","author":"Chan","year":"1985","journal-title":"Zoological Science"},{"key":"2026010712582474200_bib8","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1038\/168697b0","article-title":"Fertilizing capacity of spermatozoa deposited into the fallopian tubes","volume":"168","author":"Chang","year":"1951","journal-title":"Nature"},{"key":"2026010712582474200_bib9","doi-asserted-by":"crossref","first-page":"795","DOI":"10.1016\/0093-691X(94)90448-R","article-title":"In vitro fertilization rate of horse oocytes with partially removed zonae","volume":"42","author":"Choi","year":"1994","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib10","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1146\/annurev.bb.24.060195.000505","article-title":"Molecular and structural basis of target recognition by calmodulin","volume":"24","author":"Crivici","year":"1995","journal-title":"Annual Review of Biophysics and Biomolecular Structure"},{"key":"2026010712582474200_bib11","doi-asserted-by":"crossref","first-page":"7001","DOI":"10.1074\/jbc.M206284200","article-title":"Involvement of a Na+\/HCO\u22123 cotransporter in mouse sperm capacitation","volume":"278","author":"Demarco","year":"2003","journal-title":"Journal of Biological Chemistry"},{"key":"2026010712582474200_bib12","doi-asserted-by":"crossref","first-page":"1499","DOI":"10.1016\/j.theriogenology.2010.12.011","article-title":"Agreement between measures of total motility and membrane integrity in stallion sperm","volume":"75","author":"Foster","year":"2011","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib13","doi-asserted-by":"crossref","first-page":"707","DOI":"10.1095\/biolreprod56.3.707","article-title":"Regulation of protein tyrosine phosphorylation during bovine sperm capacitation by a cyclic adenosine 3\u20325\u2032-monophosphate-dependent pathway","volume":"56","author":"Galantino-Homer","year":"1997","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib14","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1002\/mrd.20034","article-title":"Bovine sperm capacitation: assessment of phosphodiesterase activity and intracellular alkalinization on capacitation-associated protein tyrosine phosphorylation","volume":"67","author":"Galantino-Homer","year":"2004","journal-title":"Molecular Reproduction and Development"},{"key":"2026010712582474200_bib15","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1095\/biolreprod32.1.145","article-title":"Albumin-mediated changes in sperm sterol content during capacitation","volume":"32","author":"Go","year":"1985","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib16","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/j.devcel.2005.06.007","article-title":"The \u201csoluble\u201d adenylyl cyclase in sperm mediates multiple signaling events required for fertilization","volume":"9","author":"Hess","year":"2005","journal-title":"Developmental Cell"},{"key":"2026010712582474200_bib17","doi-asserted-by":"crossref","first-page":"304","DOI":"10.1002\/(SICI)1098-2795(199811)51:3<304::AID-MRD10>3.0.CO;2-2","article-title":"Regulation of protein tyrosine phosphorylation in boar sperm through a cAMP-dependent pathway","volume":"51","author":"Kalab","year":"1998","journal-title":"Molecular Reproduction and Development"},{"key":"2026010712582474200_bib18","doi-asserted-by":"crossref","first-page":"680","DOI":"10.1038\/227680a0","article-title":"Cleavage of structural proteins during the assembly of the head of bacteriophage T4","volume":"227","author":"Laemmli","year":"1970","journal-title":"Nature"},{"key":"2026010712582474200_bib19","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1530\/jrf.0.0940023","article-title":"Decrease in calmodulin concentrations during heparin-induced capacitation in bovine spermatozoa","volume":"94","author":"Leclerc","year":"1992","journal-title":"Journal of Reproduction and Fertility"},{"key":"2026010712582474200_bib20","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1002\/j.1939-4640.1998.tb02037.x","article-title":"Interaction between Ca2+, cyclic 3\u2032,5\u2032 adenosine monophosphate, the superoxide anion, and tyrosine phosphorylation pathways in the regulation of human sperm capacitation","volume":"19","author":"Leclerc","year":"1998","journal-title":"Journal of Andrology"},{"key":"2026010712582474200_bib21","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1093\/biolreprod\/52.monograph_series1.309","article-title":"In vitro fertilization and development of in vitro-matured oocytes aspirated from pregnant mares","volume":"1","author":"Li","year":"1995","journal-title":"Biology of Reproduction Monograph"},{"key":"2026010712582474200_bib22","first-page":"180","article-title":"The CatSper ion channel and hyperactivated motility of horse spermatozoa","volume":"121S","author":"Loux","year":"2010","journal-title":"Animal Reproduction Science"},{"key":"2026010712582474200_bib23","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1095\/biolreprod55.1.207","article-title":"Extracellular calcium negatively modulates tyrosine phosphorylation and tyrosine kinase activity during capacitation of human spermatozoa","volume":"55","author":"Luconi","year":"1996","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib24","doi-asserted-by":"crossref","first-page":"1396","DOI":"10.1016\/S0015-0282(03)00267-X","article-title":"Calcium requirements for human sperm function in vitro","volume":"79","author":"Marin-Briggiler","year":"2003","journal-title":"Fertility and Sterility"},{"key":"2026010712582474200_bib25","doi-asserted-by":"crossref","first-page":"2013","DOI":"10.1242\/jcs.02326","article-title":"Evidence of the presence of calcium\/calmodulin-dependent protein kinase IV in human sperm and its involvement in motility regulation","volume":"118","author":"Marin-Briggiler","year":"2005","journal-title":"Journal of Cell Science"},{"key":"2026010712582474200_bib26","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1016\/j.theriogenology.2007.11.016","article-title":"A defined medium supports changes consistent with capacitation in stallion sperm, as evidenced by increases in protein tyrosine phosphorylation and high rates of acrosomal exocytosis","volume":"69","author":"McPartlin","year":"2008","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib27","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1095\/biolreprod.108.074880","article-title":"Hyperactivation of stallion sperm is required for successful in vitro fertilization of equine oocytes","volume":"81","author":"McPartlin","year":"2009","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib28","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1095\/biolreprod.110.085555","article-title":"Guanine-nucleotide exchange factors (RAPGEF3\/RAPGEF4) induce sperm membrane depolarization and acrosomal exocytosis in capacitated stallion sperm","volume":"85","author":"McPartlin","year":"2011","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib29","doi-asserted-by":"crossref","first-page":"919","DOI":"10.1016\/S0015-0282(99)00013-8","article-title":"Modulation of sperm tail protein tyrosine phosphorylation by pentoxifylline and its correlation with hyperactivated motility","volume":"71","author":"Nassar","year":"1999","journal-title":"Fertility and Sterility"},{"key":"2026010712582474200_bib30","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1186\/1477-7827-2-75","article-title":"Role of tyrosine phosphorylation in sperm capacitation\/acrosome reaction","volume":"2","author":"Naz","year":"2004","journal-title":"Reproductive Biology and Endocrinology"},{"key":"2026010712582474200_bib31","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1006\/jmbi.1997.1524","article-title":"Solution structure of calmodulin-W-7 complex: the basis of diversity in molecular recognition","volume":"276","author":"Osawa","year":"1998","journal-title":"Journal of Molecular Biology"},{"key":"2026010712582474200_bib32","doi-asserted-by":"crossref","first-page":"1017","DOI":"10.1093\/molehr\/5.11.1017","article-title":"Regulation of human sperm capacitation by a cholesterol efflux-stimulated signal transduction pathway leading to protein kinase A-mediated up-regulation of protein tyrosine phosphorylation","volume":"5","author":"Osheroff","year":"1999","journal-title":"Molecular Human Reproduction"},{"key":"2026010712582474200_bib33","doi-asserted-by":"crossref","first-page":"8550","DOI":"10.1016\/S0021-9258(18)32091-X","article-title":"Calmodulin-stimulated dephosphorylation of p-nitrophenyl phosphate and free phosphotyrosine by calcineurin","volume":"258","author":"Pallen","year":"1983","journal-title":"Journal of Biological Chemistry"},{"key":"2026010712582474200_bib34","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1095\/biolreprod41.4.683","article-title":"Capacitation of bovine sperm by heparin: inhibitory effect of glucose and role of intracellular pH","volume":"41","author":"Parrish","year":"1989","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib35","doi-asserted-by":"crossref","first-page":"1208","DOI":"10.1095\/biolreprod.102.011106","article-title":"Phosphorylation of protein tyrosine residues in fresh and cryopreserved stallion spermatozoa under capacitating conditions","volume":"68","author":"Pommer","year":"2003","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib36","doi-asserted-by":"crossref","first-page":"1531","DOI":"10.1016\/j.theriogenology.2005.08.022","article-title":"Capacitation-like changes in equine spermatozoa following cryopreservation","volume":"65","author":"Thomas","year":"2006","journal-title":"Theriogenology"},{"key":"2026010712582474200_bib37","doi-asserted-by":"crossref","first-page":"1031","DOI":"10.1095\/biolreprod51.5.1031","article-title":"Heparin-induced capacitation but not intracellular alkalinization of bovine sperm is inhibited by Rp-adenosine-3\u2032,5\u2032-cyclic monophosphorothioate","volume":"51","author":"Uguz","year":"1994","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib38","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1095\/biolreprod59.1.1","article-title":"Regulation of protein phosphorylation during sperm capacitation","volume":"59","author":"Visconti","year":"1998","journal-title":"Biology of Reproduction"},{"key":"2026010712582474200_bib39","doi-asserted-by":"crossref","first-page":"1129","DOI":"10.1242\/dev.121.4.1129","article-title":"Capacitation of mouse spermatozoa. I. Correlation between the capacitation state and protein tyrosine phosphorylation","volume":"121","author":"Visconti","year":"1995","journal-title":"Development"},{"key":"2026010712582474200_bib40","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1006\/dbio.1999.9428","article-title":"Cholesterol efflux-mediated signal transduction in mammalian sperm: cholesterol release signals an increase in protein tyrosine phosphorylation during mouse sperm capacitation","volume":"214","author":"Visconti","year":"1999","journal-title":"Developmental Biology"},{"key":"2026010712582474200_bib41","doi-asserted-by":"crossref","first-page":"395","DOI":"10.1038\/aja.2010.69","article-title":"Ion channels, phosphorylation and mammalian sperm capacitation","volume":"13","author":"Visconti","year":"2011","journal-title":"Asian Journal of Andrology"},{"key":"2026010712582474200_bib45","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1002\/mrd.1080400413","article-title":"Intracellular pH of bovine sperm increases during capacitation","volume":"40","author":"Vredenburgh-Wilberg","year":"1995","journal-title":"Molecular Reproduction and Development"},{"key":"2026010712582474200_bib42","doi-asserted-by":"crossref","first-page":"1317","DOI":"10.1242\/dev.00353","article-title":"Bicarbonate actions on flagellar and Ca2+-channel responses: initial events in sperm activation","volume":"130","author":"Wennemuth","year":"2003","journal-title":"Development"},{"key":"2026010712582474200_bib43","doi-asserted-by":"crossref","first-page":"35539","DOI":"10.1074\/jbc.M804586200","article-title":"Chloride is essential for capacitation and for the capacitation-associated increase in tyrosine phosphorylation","volume":"283","author":"Wertheimer","year":"2008","journal-title":"Journal of Biological Chemistry"}],"container-title":["Reproduction"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/rep.bioscientifica.com\/view\/journals\/rep\/144\/4\/411.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/academic.oup.com\/reproduction\/article-pdf\/144\/4\/411\/64535335\/411.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/academic.oup.com\/reproduction\/article-pdf\/144\/4\/411\/64535335\/411.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,7]],"date-time":"2026-01-07T18:07:15Z","timestamp":1767809235000},"score":1,"resource":{"primary":{"URL":"https:\/\/academic.oup.com\/reproduction\/article\/144\/4\/411\/8243605"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2012,10,1]]},"references-count":44,"journal-issue":{"issue":"4","published-print":{"date-parts":[[2012,10,1]]}},"URL":"https:\/\/doi.org\/10.1530\/rep-12-0067","relation":{},"ISSN":["1470-1626","1741-7899"],"issn-type":[{"value":"1470-1626","type":"print"},{"value":"1741-7899","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2012,10,1]]},"published":{"date-parts":[[2012,10,1]]}}}