title: Plant cells contain calsequestrin.
abstract: Calsequestrin is a high capacity low affinity Ca2+-binding protein thought to be essential for the function of the intracellular rapid releasable Ca2+ pool of a variety of animal cells. Here we show that two types of plant tissues, cultured Streptanthus tortuosus cells and spinach leaves, contain a form of calsequestrin. In subcellular fractions of S. tortuosus cells, Stains-all staining reveals a metachromatically blue-staining 56,000-Da protein enriched in the microsomal fraction. This protein shares several biochemical characteristics with animal calsequestrin: 1) it changes its apparent molecular weight with the pH; 2) it is able to bind 45Ca2+ on nitrocellulose transfers; and 3) it is recognized by antibodies against canine cardiac calsequestrin. Calsequestrin was also identified in spinach leaves using a direct extraction procedure that was developed for muscle calsequestrin. Thus, our results demonstrate that plant cells contain calsequestrin within a subcellular membrane fraction. These results also suggest that calsequestrin is an ubiquitous protein rather than being limited only to animal cells.
authors.affiliation: Department of Physiology and Biophysics, University of Iowa College of Medicine, Iowa City 52242.
authors.forename: K H
authors.initials: KH
authors.lastname: Krause
authors.forename: M
authors.initials: M
authors.lastname: Chou
authors.forename: M A
authors.initials: MA
authors.lastname: Thomas
authors.forename: R D
authors.initials: RD
authors.lastname: Sjolund
authors.forename: K P
authors.initials: KP
authors.lastname: Campbell
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002155:Calsequestrin / Q000032:analysis*; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D008854:Microscopy, Electron; D008861:Microsomes / Q000032:analysis; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis*; D009206:Myocardium / Q000032:analysis; D010944:Plants / Q000032:analysis* / Q000648:ultrastructure
chemical_list: D002155:Calsequestrin; D009124:Muscle Proteins; D002118:Calcium