Abstract
A MgATPase has been isolated and characterized from unfertilized sea urchin eggs which is very similar, but not identical, to latent activity axonemal dynein. The cytoplasmic MgATPase activity sediments at 20 S, slightly slower than 21 S latent activity flagellar dynein. Activity is stimulated by nonionic detergent and is inhibited by sodium orthovanadate but is not as sensitive to vanadate as is 21 S flagellar dynein. The egg 20 S MgATPase is composed, at least in part, of three high molecular weight polypeptides. In addition, two intermediate-sized polypeptides appear to co-sediment with the 20 S MgATPase activity. A novel microtubule-affinity assay reveals that high molecular weight polypeptides 1 and 2 of the egg 20 S MgATPase can bind to reassembled microtubules and can be released from the microtubules with MgATP2-. Further, the apparent specific activity of the egg MgATPase is enriched 15-fold by a single microtubule binding step. The results suggest that the cytoplasmic 20 S MgATPase is a dynein-like microtubule translocator which resides in the unfertilized egg awaiting future incorporation onto microtubules in order to perform work. The egg 20 S enzyme might function in cytoplasmic microtubule-mediated movement or it might be a precursor of embryonic ciliary dynein.
Highlights
A 20 S Latent Activity Cytoplasmic M,qATPasr--We have partially purified a MgATPase from unfertilized sea urchin eggs that possesses a number of properties in common with
The egg enzyme was isolated as a 20 S species whose apparent specific MgATPase activity could be stimulated by nonionic detergent
Specific activities of sucrose-gradient-purified flagellar and egg enzymes were very similar, and both were inhibited by vanadate, the egg MgATPase was less sensitive to vanadate than was axonemal dynein
Summary
The cytoplasmic MgATPase activity sediments at S, slightly slower than S latent activity flagellar dynein. Of the cytoplasmic MgATPase and a comparison of its prop- ATP according to the procedure of Conway and Lipmann (1964) as erties with those of axonemal dynein may lead to important new insights with respect to microtubule-based cytoplasmic motility. The costs of publi- bled sea urchin egg microtubules through the sucrose layers with an cation of this article were defrayed in part by the payment of page SW 41 rotor at 35,000 rpm for 90 min a t 18'C, and the binding of charges. Both the axonema2l1 S dynein and thegg 20 S MgATPase were isolated in identical sucrose gradients, stimulated with silver (Merril v/ nl., 1981). Protein concentration was determined hy 0.20% (v/v) Triton X-100, and analyzed hv a [y-~'"I']ATl'ase t h e n ~ e t h o do f 1,owry v f nl. (1951) using bovine serum alhumin as a assay.Theactivatedflagellardyneinpossessedaspecific standard
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
