JPH1 (junctophilin 1) is a structural protein essential for forming junctional membrane complexes that link the plasma membrane to the sarcoplasmic reticulum in skeletal muscle 1. JPH1 anchors to the sarcoplasmic reticulum via its C-terminal transmembrane domain while binding the transverse tubule membrane through N-terminal lipid-binding MORN motifs, thereby tethering these membranes to form triads 2. This organization supports voltage-induced calcium release and excitation-contraction coupling 3. Mechanistically, JPH1 forms homo- and heterodimeric interactions with JPH2, which stabilizes its recruitment at triads 2. JPH1 participates in store-operated calcium entry (SOCE) regulation and colocalizes with STIM1 at ER-plasma membrane contact sites 4. JPH1 associates with Huntingtin protein to modulate calcium fluxes 5. Disease relevance includes congenital myopathy 25 and genetic modification of Charcot-Marie-Tooth disease severity; JPH1 mutations impair SOCE rescue in GDAP1-related CMT2K 4. Reduced JPH1 protein levels cause skeletal myopathy and muscle weakness 1. Additionally, JPH1 expression correlates with liver metastasis risk in colorectal and breast cancers 6.