The heart LIM protein (HLP) is a LIM-only protein family member that mediates protein protein interactions. To date, no studies have yet been conducted regarding its function in the heart. In the present study, we have identified that HLP binds the cytosolic region of RyR2 in the heart using a bacterial two-hybrid system, LC-MS/MS, co-immunoprecipitation, and GST-pull down assays. Microscopy revealed that HLP forms a triple complex with RyR2 and caveolin-3. siRNA and adenovirus-mediated MD of HLP decreased the electrically evoked Ca2+ release from the sarcoplasmic reticulum without directly affecting SERCA2 and RyR2 activities. Collectively, the HLP-RyR2 interaction in the cell surface caveolae region may be essential for efficient excitation-contraction coupling in the heart. (C) 2015 Elsevier Inc. All rights reserved.