Association of calmodulin with isolated nuclei from rat hepatocytes.
Calmodulin plays an important role in regulating cell proliferation and intranuclear processes (J. Biol. Chem. 265: 18595, 1990). Therefore we studied the association of 125I-calmodulin with highly purified rat hepatocyte nuclear preparations which were characterized by marker enzymes and electron microscopy. Steady-state association of 125I-calmodulin was reached within 5 minutes. Half-maximal binding was achieved at approximately 7.1 microM. This association was partially Ca(2+)-dependent, but was not influenced by ATP, GTP or wheat germ agglutinin. Ultrastructural autoradiography showed specific association of 125I-calmodulin with peripheral and non-peripheral heterochromatin, nuclear membranes, and nucleoli. Specific binding (ratio of the grain density of 125I-calmodulin to Na125I) was greatest in the regions of the nucleoli and non-peripheral heterochromatin. The data indicate that exogenous calmodulin can associate with specific nuclear components in an energy-independent and Ca(2+)-dependent manner.
Wong
E C
EC
Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110.
Saffitz
J E
JE
McDonald
J M
JM
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006570:Heterochromatin / Q000378:metabolism; D007457:Iodine Radioisotopes; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000378:metabolism; D051381:Rats
D002147:Calmodulin; D002843:Chromatin; D006570:Heterochromatin; D007457:Iodine Radioisotopes; D004533:Egtazic Acid; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate