title: Evidence for a Ca2+-binding protein associated to non-actin microfilamentous systems in two ciliated protozoans.
abstract: Electrophoretic distributions of proteins of isolated cortical cytoskeletons from two ciliated protozoans (Isotricha, Polyplastron) were compared in order to reveal any components common to non-actin microfilamentous structures. A low molecular weight protein (Mr approximately 22 kD) characterized by Ca2+-induced shifts in mobility on SDS-polyacrylamide gels was identified in both ciliates. Two-dimensional electrophoretic coordinates and peptide maps of Ca2+-binding proteins from Isotricha and Polyplastron are fairly similar, suggesting conservation of the same molecular species. In addition, an antiserum raised against two proteins (22-23 KD) from the filamentous ecto-endoplasmic boundary of Isotricha, one of which corresponds to the Ca2+-binding protein, cross-reacts specifically with that of Polyplastron. Using an immunogold staining procedure, the Ca2+-binding protein of Polyplastron was shown also to be located in a cortical microfilamentous layer. This protein is probably different from calmodulin. We postulate that it is involved in the control of the ordering of non-actin microfilaments within the cortex of ciliates.
mesh_terms: D002135:Calcium-Binding Proteins / Q000032:analysis*; D016798:Ciliophora / Q000378:metabolism*; D003599:Cytoskeleton / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D007158:Immunologic Techniques; D007526:Isoelectric Point; D010455:Peptides / Q000032:analysis
chemical_list: D002135:Calcium-Binding Proteins; D010455:Peptides