title: The distribution of calmodulin in living mitotic cells.
abstract: Calmodulin has been labeled with rhodamine isothiocyanate (CaM-RITC) and used as a probe for the location of calmodulin in vivo. CaM-RITC retains its capacity to regulate the activity of brain phosphodiesterase in a Ca2+-dependent manner in vitro, indicating that the labeled protein is still active. After injection into living mammalian cells CaM-RITC incorporates rapidly into the mitotic spindle; the details of its localization there mimic closely the distribution of calmodulin seen by immunofluorescence. In interphase cells the CaM-RITC is excluded from the nucleus, but shows no region of specific concentration within the cytoplasm. Neither a 2-fold increase in cellular CaM nor the injection of anti CaM has any observable effect on the progress of mitosis.
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000032:analysis*; D002460:Cell Line; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000032:analysis; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D007614:Macropodidae; D051379:Mice; D008845:Microinjections; D008938:Mitosis; D012235:Rhodamines; D008941:Spindle Apparatus / Q000032:analysis*
chemical_list: D002147:Calmodulin; D012235:Rhodamines; C027755:rhodamine isothiocyanate