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Gene Review

LOC373457  -  speract protein

Strongylocentrotus purpuratus

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High impact information on LOC373457

  • A. punctulata spermatozoa do not respond to speract, a peptide isolated from the jelly layer of Strongylocentrotus purpuratus eggs [1].
  • Activation of Na+:H+ exchange without speract by either Na+ addition to sperm in Na+-free seawater (NaFASW) or by monensin also increases [Ca2+]i, but neither change is transient [2].
  • Increasing pHi by adding 10 mM NH4+ or by addition of Li+ to sperm in NaFASW does not increase [Ca2+]i. The data suggest that speract binding leads to rapid activation of Na+:H+ exchange; and, as a consequence, [Ca2+] entry increases transiently through either Na+:Ca2+ exchange or else through a verapamil-insensitive Ca2+ channel [2].
  • However, membrane potential depolarization did not occur when the activation was induced by increased extracellular pH or by the peptide speract, although activation was always linked to increased intracellular pH [3].
  • The peptide, purified from Strongylocentrotus purpuratus eggs, also cross-reacts with spermatozoa from Lytechnis pictus sea urchins, suggesting that speract does not show species specificity [4].

Biological context of LOC373457

  • A complementary DNA clone (2.3 kb) that encodes the egg peptide speract (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly) has been isolated from an ovary cDNA library of the sea urchin [5].
  • Inhibition of Na+:H+ exchange by increased seawater [K+] prevents the rise in [Ca2+]i initiated by either speract or Na+ addition to sperm in NaFASW [2].
  • Speract is a potent stimulator of sea urchin sperm oxygen consumption, causing significant increases of sperm respiration rates at concentrations as low as 10(-12) M and producing 20-fold increases of oxygen consumption at maximal concentrations of 10(-8) M [4].
  • Speract, a peptide of S. purpuratus may act as a chemoattractant as well or may serve functions other than chemotaxis [6].
  • Competition binding studies with the fluorescent peptide and intact spermatozoa yielded IC50 values which were indistinguishable from native speract and GGG[Y2]-speract (approximately 20 nM) [7].

Anatomical context of LOC373457


Associations of LOC373457 with chemical compounds

  • An apparent receptor for the egg peptide speract (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly) was identified by covalently coupling a radiolabeled speract analogue to intact spermatozoa and was then purified by DEAE-Sepharose chromatography and preparative gel electrophoresis after solubilization with Lubrol PX [9].
  • Sperm cyclic GMP and cyclic AMP concentrations are also increased by speract, but concentrations of at least 10(-10) M and 10(-9) M are required for half-maximal elevations, respectively [4].
  • A low molecular weight peptide (speract) associated with sea urchin eggs has been purified to apparent homogeneity by charcoal adsorption, DEAE-Sephacel chromatography, Bio-Gel P-2 filtration, and Dowex AG 50W-X4 chromatography [4].
  • Speract is composed entirely of neutral and acidic amino acids with glycine as the major component, and it appears to have a blocked NH2 terminus based on its insensitivity to leucine aminopeptidase, its failure to react with dansyl chloride, and its chromatographic behavior on strong cation exchange resins [4].
  • In contrast, hyperpolarization responses to speract are increased by 3-isobutyl-1-methylxanthine, which preferentially inhibits cGMP-selective phosphodiesterases of sperm, and the 8Br-cGMP derivative hyperpolarizes vesicles in the absence of speract [10].


  1. Chemotaxis of Arbacia punctulata spermatozoa to resact, a peptide from the egg jelly layer. Ward, G.E., Brokaw, C.J., Garbers, D.L., Vacquier, V.D. J. Cell Biol. (1985) [Pubmed]
  2. Alteration of intracellular [Ca2+] in sea urchin sperm by the egg peptide speract. Evidence that increased intracellular Ca2+ is coupled to Na+ entry and increased intracellular pH. Schackmann, R.W., Chock, P.B. J. Biol. Chem. (1986) [Pubmed]
  3. Measurement of plasma membrane and mitochondrial potentials in sea urchin sperm. Changes upon activation and induction of the acrosome reaction. Schackmann, R.W., Christen, R., Shapiro, B.M. J. Biol. Chem. (1984) [Pubmed]
  4. Speract. Purification and characterization of a peptide associated with eggs that activates spermatozoa. Hansbrough, J.R., Garbers, D.L. J. Biol. Chem. (1981) [Pubmed]
  5. A single mRNA encodes multiple copies of the egg peptide speract. Ramarao, C.S., Burks, D.J., Garbers, D.L. Biochemistry (1990) [Pubmed]
  6. Revisiting the role of H+ in chemotactic signaling of sperm. Solzin, J., Helbig, A., Van, Q., Brown, J.E., Hildebrand, E., Weyand, I., Kaupp, U.B. J. Gen. Physiol. (2004) [Pubmed]
  7. Speract receptors are localized on sea urchin sperm flagella using a fluorescent peptide analog. Cardullo, R.A., Herrick, S.B., Peterson, M.J., Dangott, L.J. Dev. Biol. (1994) [Pubmed]
  8. Co-localization of receptor and transducer proteins in the glycosphingolipid-enriched, low density, detergent-insoluble membrane fraction of sea urchin sperm. Ohta, K., Sato, C., Matsuda, T., Toriyama, M., Vacquier, V.D., Lennarz, W.J., Kitajima, K. Glycoconj. J. (2000) [Pubmed]
  9. Cloning of the mRNA for the protein that crosslinks to the egg peptide speract. Dangott, L.J., Jordan, J.E., Bellet, R.A., Garbers, D.L. Proc. Natl. Acad. Sci. U.S.A. (1989) [Pubmed]
  10. Participation of a K(+) channel modulated directly by cGMP in the speract-induced signaling cascade of strongylocentrotus purpuratus sea urchin sperm. Galindo, B.E., Beltrán, C., Cragoe, E.J., Darszon, A. Dev. Biol. (2000) [Pubmed]
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