May serve as an anchoring protein that mediates the subcellular compartmentation of protein kinase A (PKA) via binding to PRKAR2A (By similarity). May function as a repressor of calcineurin-mediated transcriptional activity. May attenuate calcineurin ability to induce slow-fiber gene program in muscle and may negatively modulate skeletal muscle regeneration (By similarity). Plays a role in the assembly of ryanodine receptor (RYR2) clusters in striated muscle (By similarity). Interacts with PRKAR2A. Interacts with ACTN2 and DTNBP1/dysbindin (By similarity). Interacts with DES (PubMed:17872945). Interacts with DMD/dystrophin (By similarity). Interacts with the calcineurin catalytic subunit PPP3CA (By similarity). Interacts with TTN (PubMed:20634290). Interacts with CAPN3; this interaction, which results in CMYA5 proteolysis, may protect CAPN3 from autolysis (PubMed:20634290). Interacts with FSD2 (By similarity). Identified in a complex composed of FSD2, CMYA5 and RYR2 (By similarity). Found predominantly at the periphery of the nucleus but also throughout the cell. Localized in lysosomes (By similarity). In skeletal muscles, localizes along myofiber periphery, at costameres (By similarity). Predominantly flanks Z-disks (By similarity). Occasionally present at the M-band level. Colocalized with RYR2 in the sarcoplasmic reticulum (By similarity). Expressed in skeletal muscle; at a strong level and in heart. Down-regulated in muscle cell lines derived from patients with Duchenne muscular dystrophy (DMD). Amphipathic helix regions act as an anchoring domain for PKA, and appear to be responsible of the interaction between myospryn and PRKAR2A. Phosphorylated by PKA. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence. Truncated C-terminus. Truncated N-terminus. Contaminating sequence. Potential poly-A sequence.