Manduca sexta vitellogenin is a phosphoglycolipoprotein (Mᵣ ∼ 500,000) that contains two copies of the apoproteins (apovitellogenin-I, Mᵣ 180,000 and apovitellogenin-II Mᵣ 45,000), 13 percent lipids, 3 percent carbohydrates and 0.6 percent phosphorus. The two apoproteins are immunologically distinct and apovitellogenin-II is not completely accessible to the aqueous environment in the intact molecule. The carbohydrate moiety located on apovitellogenin-I has a high mannose structure (Man₉ GlcNAc₂). Follicle membranes bind ¹²⁵I-labeled vitellogenin with high affinity and specificity (K(D) ≃ 1.3 x 10⁻⁸ M). Total binding sites were estimated at 4 x 10¹⁴ sites/g of follicle membrane protein. The binding was sensitive to pH and calcium. Competition studies showed that binding of vitellogenin was blocked by vitellin and deglycosylated vitellogenin but not by lipophorin, microvitellogenin or apovitellogenin-II. These results suggest that the uptake of vitellogenin involves binding to specific receptors on follicle membranes and the carbohydrate moiety and apovitellogenin-II are not involved in the interaction with the receptors.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/188160 |
| Date | January 1986 |
| Creators | OSIR, ELLIE ONYANGO. |
| Contributors | Law, John H., Wells, Michael, Grimes, William, Tischler, Marc, Berry, James, Price, Ralph |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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