Acts as a calcium sensor. CBL proteins interact with CIPK serine-threonine protein kinases. Binding of a CBL protein to the regulatory NAF domain of a CIPK protein lead to the activation of the kinase in a calcium-dependent manner. Mediates salt tolerance, but only when phosphorylated. Competes with CIPK23 for a direct binding to AKT1, negatively regulating its activity via a protein kinase-independent mechanism. Homodimer (By similarity). Interacts with CIPK24 and AKT1. Exclusively targeted to the tonoplast when interacting with CIPK24 (PubMed:19832944). PubMed:17449811 indicates a cell membrane localization while PubMed:17825054 shows a vacuole membrane and endosome localization. Expressed in shoots, leaves, stems, flowers and siliques. Barely detected in roots. Not induced by abiotic stresses. The N-terminal 40 amino acids are necessary and sufficient for vacuolar and endosomal targeting. Phosphorylated by CIPK24. The level of phosphorylation is enhanced by CIPK24-CBL10 interaction. The phosphorylation is induced by salt stress and limited to membrane-bound CBL10. No visible phenotype when grown under normal conditions but hypersensitivity to salt stress. May be due to a competing donor splice site. Belongs to the calcineurin regulatory subunit family.