title: Discrete subcellular localization of a cytoplasmic and a mitochondrial isozyme of creatine kinase in intestinal epithelial cells.
abstract: Two isozymes of creatine kinase have been purified differentially from mitochondrial and cytoplasmic subfractions of intestinal epithelial cells. These intestinal epithelial cell creatine kinases were indistinguishable from the cytoplasmic (B-CK) and mitochondrial (Mi-CK) creatine kinase isozymes of brain when compared by SDS-PAGE, cellulose polyacetate electrophoresis, and peptide mapping. In intestinal epithelial cells, immunolocalization of the Mi-CK isozyme indicates that it is associated with long, thin mitochondria, which are excluded from the brush border at the apical end of each cell. In contrast, immunolocalization of the B-CK isozyme indicates that it is concentrated distinctly in the brush border terminal web domain. Although absent from the microvilli, B-CK also is distributed diffusely throughout the cytoplasm. Terminal web localization of B-CK was maintained in glycerol-permeabilized cells and in isolated brush borders, indicating that B-CK binds to the brush border structure. The abundance and localization of the mitochondrial and cytoplasmic creatine kinase isozymes suggest that they are part of a system that temporally and/or spatially buffers dynamic energy requirements of intestinal epithelial cells.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee 32312-3050.
authors.forename: T C
authors.initials: TC
authors.lastname: Keller
authors.forename: P V
authors.initials: PV
authors.lastname: Gordon
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D002645:Chickens; D003402:Creatine Kinase / Q000276:immunology / Q000302:isolation & purification*; D003593:Cytoplasm / Q000737:chemistry / Q000201:enzymology* / Q000648:ultrastructure; D004386:Duodenum / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D007527:Isoenzymes / Q000276:immunology / Q000302:isolation & purification*; D008871:Microvilli / Q000201:enzymology / Q000648:ultrastructure; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology* / Q000648:ultrastructure; D010449:Peptide Mapping
chemical_list: D000906:Antibodies; D007527:Isoenzymes; D003402:Creatine Kinase