Two isozymes of creatine kinase (CK) were partially purified from isolated intestinal epithelial cells and identified as the non-muscle cytoplasmic isoform (B-CK) and the non-muscle mitochondrial isoform (Mi-CK). In intestinal epithelia, mitochondria (and Mi-CK) are excluded from the dense cytoskeletal web underlying the microvillar brush border. There are two myosin II subsets in this domain. The first cross-links the descending microvillar rootlets while the second is organized within a circumferential contractile ring. In glycerinated cells and isolated brush borders both interrootlet myosin solubilization and ring contraction were supported by the addition of creatine phosphate (Cr-P) to the endogenous B-CK-based ATP-regenerating system. When an exogenous ATP hydrolysis system was added (hexokinase and 25 mM glucose) both solubilization and contraction were supported in glycerinated cells, but only contraction was supported in isolated brush borders. Immunofluorescent imaging of B-CK revealed a marked loss in isolated brush borders compared to that of glycerinated cells, indicating that the interrootlet myosin-coupled B-CK subset had been extracted. These differential B-CK-myosin interactions were exploited to demonstrate ATP compartmentation between B-CK and ring myosin. Comparisons of epithelia from duodenum, jejunum, and ileum reveal that both contractile ring and interrootlet myosin-B-CK interactions are maintained despite the lower endogenous B-CK concentrations observed in the jejunum and ileum. / Source: Dissertation Abstracts International, Volume: 53-07, Section: B, page: 3260. / Major Professor: Thomas C. S. Keller, III. / Thesis (Ph.D.)--The Florida State University, 1992.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76703 |
| Contributors | Gordon, Phillip Van., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 108 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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