Estrogen-induced hepatic contributions to ovarian follicle development in Fundulus heteroclitus: Vitellogenins and choriogenins
We have increased our chances of isolating cDNAs that code for estrogen-induced proteins by constructing a liver cDNA library from the poly A$\sp+$RNA of Fundulus heteroclitus treated with estradiol-17$\beta.$ We report cDNAs coding for two vitellogenins (Vtg I and Vtg II) and three novel proteins t...
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| Format: | Dissertation |
| Language: | English |
| Published: |
ProQuest Dissertations & Theses
01-01-1996
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| Online Access: | Get full text |
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| Summary: | We have increased our chances of isolating cDNAs that code for estrogen-induced proteins by constructing a liver cDNA library from the poly A$\sp+$RNA of Fundulus heteroclitus treated with estradiol-17$\beta.$ We report cDNAs coding for two vitellogenins (Vtg I and Vtg II) and three novel proteins that share identity with mammalian ZP proteins. We have designated the latter proteins as "choriogenins" to highlight their role as components of the vitelline envelope and chorion, yet to emphasize their site of synthesis as being extra-ovarian, and thus different from that of the mammalian ZP proteins. Conceptual translations of the F. heteroclitus Vtg I and II cDNAs share 60% sequence identity with each other and 30% identity with other reported vertebrate Vtgs. The N-terminus of a 69 kDa yolk protein matched the predicted N-terminus of Vtg II (minus a signal peptide), verifying that Vtg II is expressed without being N-terminally blocked. Six other yolk proteins were mapped to the predicted Vtg I sequence, confirming that Vtg I represents the major yolk protein precursor. A 125-kDa yolk protein that is specifically degraded during final maturation was mapped to a region of the Vtg I sequence that contained a PEST site, suggesting an explanation for its preferential break-down. The three choriogenins were referred to as Chg 500, Chg 427, and Chg 553, according to the number of amino acids predicted for each protein. Chg 500 and 553 were found to be 58% identical to a flounder "zp gene product", and 30% identical with the mouse ZP1 protein. Chgs 500 and 553 contain proline-glutamine-rich repeating regions that resemble a PXX motif reported in other extracellular matrix proteins. Chg 427 was found to be 67% identical to a medaka "L-SF protein" and 30% identitical to the mouse ZP3 protein that has been implicated as the primary sperm receptor. Besides reporting the sequences of five hepatically-derived proteins that contribute to the development of the ovarian follicle, we emphasize that the estrogen-induced library is an excellent strategy to screen for reproductively significant cDNAs. |
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| ISBN: | 9780591100167 0591100169 |