Purified lipophorin, metabolically labelled with 32P exclusively in the phospholipid moiety, was used to study the process of phospholipid delivery to the oocyte. The kinetics of phospholipid transfer "in vitro," from lipophorin to the oocytes, was linear at least up to 4 h and was impaired by low t
Identification of yolk platelet-associated hydrolases in the oocytes of Rhodnius prolixus
β Scribed by Roberto H. Nussenzveig; Pedro L. Oliveira; Hatisaburo Masuda
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 588 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0739-4462
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β¦ Synopsis
The yolk platelets from Rhodnius prolixus, a blood-sucking bug, are composed mostly of vitellin and here are shown to contain at least two hydrolytic enzymes, a phosphatase and a cathepsin D-like proteinase. Both the proteinase and the phosphatase have an acid p H optimum. No hydrolytic activity was observed under alkaline or neutral conditions. Among several proteinase inhibitors tested, only pepstatin could abolish vitellin breakdown in vitro. The proteinase appears to be bound to the yolk platelet membranes. The phosphatase activity, using p-nitrophenyl phosphate a5 substrate, was enhanced after disruption of the platelet membrane by Triton X-l 00. This activity could be inhibited by tartrate but not by p-cloromercuribenzoate.
π SIMILAR VOLUMES
## Abstract Inorganic polyphosphate (poly P) is a polymer of phosphate residues that has been shown to act as modulator of some vertebrate cathepsins. In the egg yolk granules of __Rhodnius prolixus__, a cathepsin D is the main protease involved in yolk mobilization and is dependent on an activatio