During physiological contraction in striated muscle cells, the electrical signal of depolarization is converted into the Ca2+ release signal mediated by ryanodine receptors in the sarcoplasmic reticulum. In order to function as efficient intracellular stores, the sarcoplasmic reticulum is equipped with synergistically acting Ca2+ uptake, storage and release machinery, comprising of cytoplasmic, integral-membrane and luminally located proteins. Although major Ca2+-handling proteins have already been identified and extensively studied, there are still as-yet-unknown proteins in the sarcoplasmic reticulum and their roles remain to be clarified in future studies. We utilized a unique immuno-proteomic approach to generate a monoclonal antibody library that targets major proteins localized to skeletal muscle membrane systems in order to identify proteins with a key role in enabling efficient Ca2+ store functions. In the course of screening novel membrane proteins, we identified several important sarcoplasmic reticulum proteins including junctophilins and TRIC (trimeric intracellular cation) channels. Junctophilin subtypes form junctional membrane complexes between the plasma membrane and the endo/sarcoplasmic reticulum in excitable cells. TRIC channel subtypes act as novel monovalent cation-specific channels on intracellular membrane systems in various cell types. Our observations from knockout mice have provided evidence that both junctophilins and TRIC channels support ryanodine receptor-mediated Ca2+ release in striated muscle cells. Moreover, mutations and polymorphisms in the human junctophilin and TRIC channel genes are associated with hypertension risk and genetic diseases including cardiac hypertrophy and osteogenesis imperfecta. This communication will focus on the physiological and pathological roles of junctophilin and TRIC channel subtypes.