Regulatory subunit of Kv4/D (Shal)-type voltage-gated rapidly inactivating A-type potassium channels (PubMed:14980206). Regulates channel density, inactivation kinetics and rate of recovery from inactivation in a calcium-dependent and isoform-specific manner (PubMed:14980206). Modulates KCND2/Kv4.2 currents (PubMed:14980206). In vitro, modulates KCND1/Kv4.1 currents (By similarity). Increases the presence of KCND2 at the cell surface (PubMed:14980206). Component of heteromultimeric potassium channels (PubMed:15356203, PubMed:14980206). Identified in potassium channel complexes containing KCND1, KCND2, KCND3, KCNIP1, KCNIP2, KCNIP3, KCNIP4, DPP6 and DPP10 (By similarity). Part of a heterooctamer composed of the tetrameric channel and four KCNIP1 chains (By similarity). Interacts with KCND3 and the N-terminal domain of KCND2. Probably part of a complex consisting of KCNIP1, KCNIP2 isoform 3 and KCND2 (PubMed:14980206). Self-associates to form homodimers and homotetramers. Interacts with KCNIP2 isoform 3 in a calcium-dependent manner. Detected in hippocampus and in the molecular layer of the dentate gyrus (at protein level) (PubMed:15356203). Isoform 1 and isoform 2 are predominantly expressed at equal levels in brain. Colocalizes with KCND3 in inhibitory interneurons in cortex and hippocampus and in striatal interneurons. Belongs to the recoverin family.