Regulatory subunit of Kv4/D (Shal)-type voltage-gated rapidly inactivating A-type potassium channels. Modulates channel density, inactivation kinetics and rate of recovery from inactivation in a calcium-dependent and isoform-specific manner (PubMed:20943905, PubMed:23713033). In vitro, modulates KCND2/Kv4.2 and KCND3/Kv4.3 currents. Involved in KCND2 and KCND3 trafficking to the cell surface. Essential for the expression of I(To) currents in the heart (PubMed:11747815, PubMed:23713033). Required for normal protein levels of KCND2 in the heart ventricle (PubMed:23713033). Component of heteromultimeric potassium channels (PubMed:19713751, PubMed:20943905). Identified in potassium channel complexes containing KCND1, KCND2, KCND3, KCNIP1, KCNIP2, KCNIP3, KCNIP4, DPP6 and DPP10 (PubMed:19713751). The KCND2-KCNIP2 channel complex contains four KCND2 and four KCNIP2 subunits. Probably part of a complex consisting of KCNIP1, KCNIP2 isoform 3 and KCND2. At least isoform 2 and isoform 3 can self-associate to form homodimers and homotetramers. Isoform 3 interacts with KCNIP1 in a calcium-dependent manner (By similarity). Interacts with KCND2 (PubMed:20943905). Isoform 1 and isoform 3 interact with KCND3 isoform 1. Detected on lipid rafts (By similarity). Detected in brain (at protein level) (PubMed:23713033). Expressed in brain. Highly expressed in layer IV of the cerebral cortex and in striatum and hippocampus, but expressed at low levels in cerebellum. Also expressed in heart. According to PubMed:11747815 expressed in heart at much higher levels than in brain with a preferential expression in the myocardium. Palmitoylated. Palmitoylation enhances association with the plasma membrane. Mice appear healthy and show no signs of cardiac dysmorphogenesis, contractile dysfunction, hypertrophy, or heart failure but are highly susceptible to the induction of polymorphic ventricular tachycardia, including arrhythmia (PubMed:11747815, PubMed:23713033). Myocytes show a complete and selective loss of I(To) current in the heart (PubMed:11747815, PubMed:23713033). This is due to the loss of KCND2 protein in the heart ventricles (PubMed:23713033). Belongs to the recoverin family.