No plastidial calmodulin-like proteins detected by two targeted mass-spectrometry approaches and GFP fusion proteins

CaM-like proteins (CMLs) are localized in the cytosol and others in organelles such as the mitochondria, the peroxisomes and the vacuole. To date, although several plastidial proteins were identified as CaM/CML interactors, no CMLs were assigned to the chloroplast. Absence of clues about the genetic identity of plastidial CMLs prevents investigating their regulatory role. To improve our understanding of plastidial Ca2+ regulation, we attempted to identify plastidial CMLs with two large scale, CaM-specific proteomic approaches, and GFP-fusions. Despite the use of several different approaches no plastidial CML could be identified. GFP fusion of CML 35 CML36 and CML41 indicate a cytosolic localization.