An attempt to develop a short and reliable method of caldesmon purification led to the development of three procedures of caldesmon purification. The first method was seldom used because of its low yield and the lack of caldesmon endogenous kinase activity. However, it allowed us to purify MLCK (myosin light chain kinase). The second and third methods gave respectively, a caldesmon sample with and without kinase activity. We were able to localize the endogenous kinase in the 0-30% ammonium sulfate precipitated DEAE pellet but we were unsuccessful at purifying the kinase to homogeneity. We found that caldesmon can also be phosphorylated by rat brain Ca²⁺-calmodulin-dependent kinase II at sites identical to those of caldesmon endogenous kinase but different to those of kinase C. In addition, caldesmon and its endogenous kinase are two different proteins. Furthermore, our study of caldesmon inhibition of actomyosin ATPase activity showed that further research needs to be done to refute F-actin bundling process as a possible cause of caldesmon inhibition of actomyosin ATPase activity. In addition, our studies of caldesmon inhibition of HMM and S-1 ATPase activity suggest that S-2 might be partially involved in the inhibition mechanism. Finally, caldesmon did not affect the 6S-10S transition of myosin conformation and since caldesmon cannot compete against higher affinity calmodulin-binding protein such as MLCK thus, the flip-flop theory is untenable.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/184604 |
| Date | January 1988 |
| Creators | Abougou, Jean-Claude |
| Contributors | Allen, Ronald E., Hartshorne, David J., Sunde, Roger, Goll, Darrel E. |
| 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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