A Proteomics Analysis of Calmodulin-Binding Proteins in during the Transition from Unicellular Growth to Multicellular Development.

Calmodulin (CaM) is an essential calcium-binding protein within eukaryotes. CaM binds to calmodulin-binding proteins (CaMBPs) and influences a variety of cellular and developmental processes. In this study, we used immunoprecipitation coupled with mass spectrometry (LC-MS/MS) to reveal over 500 putative CaM interactors in the model organism . Our analysis revealed several known CaMBPs in and mammalian cells (e.g., myosin, calcineurin), as well as many novel interactors (e.g., cathepsin D). Gene ontology (GO) term enrichment and Search Tool for the Retrieval of Interacting proteins (STRING) analyses linked the CaM interactors to several cellular and developmental processes in including cytokinesis, gene expression, endocytosis, and metabolism. The primary localizations of the CaM interactors include the nucleus, ribosomes, vesicles, mitochondria, cytoskeleton, and extracellular space. These findings are not only consistent with previous work on CaM and CaMBPs in , but they also provide new insight on their diverse cellular and developmental roles in this model organism. In total, this study provides the first in vivo catalogue of putative CaM interactors in and sheds additional light on the essential roles of CaM and CaMBPs in eukaryotes.