Positive regulator of myogenesis. Acts as cofactor for myogenic bHLH transcription factors such as MYOD1, and probably MYOG and MYF6. Enhances the DNA-binding activity of the MYOD1:TCF3 isoform E47 complex and may promote formation of a functional MYOD1:TCF3 isoform E47:MEF2A complex involved in myogenesis (PubMed:7954791, PubMed:9234731). Plays a crucial and specific role in the organization of cytosolic structures in cardiomyocytes. Could play a role in mechanical stretch sensing. May be a scaffold protein that promotes the assembly of interacting proteins at Z-line structures. It is essential for calcineurin anchorage to the Z line. Required for stress-induced calcineurin-NFAT activation. The role in regulation of cytoskeleton dynamics by association with CFL2 is reported conflictingly. Proposed to contribute to the maintenance of muscle cell integrity through an actin-based mechanism. Can directly bind to actin filaments, cross-link actin filaments into bundles without polarity selectivity and protect them from dilution- and cofilin-mediated depolymerization; the function seems to involve its self-association. In vitro can inhibit PKC/PRKCA activity. Proposed to be involved in cardiac stress signaling by down-regulating excessive PKC/PRKCA signaling (By similarity). Self-associates. Oligomeric in the cytoplasm and monomeric in the nucleus (PubMed:16963613). Homooligomers preferentially form along the actin cytoskeleton (By similarity). Interacts with TCAP, ACTN2 and NRAP (By similarity). Interacts with LDHD, SPTB, MYOD1, MYOG, MYF6. Interacts with GLRX3 (via C-terminus); GLRX3 and calcineurin compete for interaction with CSRP3 (PubMed:9234731, PubMed:10751147, PubMed:12127981, PubMed:18258855). Interacts with CFL2; the stoichiometry influences F-actin depolymerization and possibly two molecules of CFL2 can interact with one molecule of CSRP3 resulting in the highest functional impact; the interaction is stronger with phosphorylated CFL2 (By similarity). Nucleocytoplasmic shuttling protein (PubMed:19376126). Mainly cytoplasmic. In the Z line, found associated with GLRX3 (By similarity). High in striated muscle and adult heart. LIM zinc-binding domain 1 is required for self-association. LIM zinc-binding domain 1 and LIM zinc-binding domain 2 both are required for optimal actin-bundling activity (By similarity). LIM zinc-binding domain 1 mediates binding to MYOD1. LIM zinc-binding domain 2 mediates binding to SPTB (PubMed:9234731, PubMed:10751147). Phosphorylated by PKC/PRKCA.