Premium
Calmodulin‐stimulated calcium pumping ATPases located at higher plant intracellular membranes: a significant divergence from other eukaryotes?
Author(s) -
Evans David E.
Publication year - 1994
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1994.tb00408.x
Subject(s) - calmodulin , calcium pump , endoplasmic reticulum , intracellular , calcium , cytosol , atpase , plant cell , diaphragm pump , biochemistry , biology , microbiology and biotechnology , chemistry , biophysics , enzyme , gene , materials science , organic chemistry , micropump , nanotechnology
The plasma membrane (PM) of all eukaryotes so far investigated contains a P‐type Ca 2+ ‐pumping ATPase responsible for maintaining low cytosolic free calcium concentrations. In animal cells this has been shown to be a type of Ca 2+ ‐pump which is directly stimulated by binding the calcium‐dependent regulator protein calmodulin. These PM Ca 2+ ‐pumps have been named ‘PM‐type’ as they appear to be exclusively located at the PM and not in intracellular membrane (IM) fractions. Recent progress on higher plant cells reveals that they possess calmodulin‐stimulated Ca 2+ ‐pumps of the ‘PM‐type’. However, these calmodulin‐stimulated Ca 2+ ‐pumps appear to be located not only at the PM but also in intracellular membranes, probably the endoplasmic reticulum (ER). The evidence is also convincing that these IM‐located Ca 2+ ‐pumps are directly stimulated by calmodulin (possess a calmodulin‐binding region) and are true ‘PM‐type’ Ca 2+ ‐pumps. This appears to represent a marked divergence between plant and animal cell Ca 2+ ‐pumps. Recently, molecular cloning has revealed that plant cells also contain a Ca 2+ ‐pump which is not directly stimulated by calmodulin and which strongly resembles the mammalian ER/SR type of Ca 2+ ‐pump. The significance of these findings for plant cell function is discussed.