Muscle-specific filamin, which plays a central role in sarcomere assembly and organization (PubMed:34405687). Critical for normal myogenesis, it probably functions as a large actin-cross-linking protein with structural functions at the Z lines in muscle cells. May be involved in reorganizing the actin cytoskeleton in response to signaling events (By similarity). Homodimer; the filamin repeat 24 and the second hinge domain are important for dimer formation. Interacts with FLNB, INPPL1, ITGB1A, KCND2, MYOT, MYOZ1 and MYOZ3. Interacts with sarcoglycans SGCD and SGCG. Interacts (via filament repeats 17-18, 20-21 and 24) with USP25 (isoform USP25m only). Interacts with FBLIM1. Interacts with XIRP1; this interaction is mediated by filamin 20 repeat. Interacts with KY. Interacts with IGFN1 (By similarity). Interacts with MICALL2 (By similarity). Interacts with ANK3. Interacts with SYNPO2. A small amount localizes at membranes. In striated muscle cells, it predominantly localizes in myofibrillar Z lines, while a minor fraction localizes with subsarcolemme. Targeting to developing and mature Z lines is mediated by the intradomain insert. Highly expressed in striated muscles. Weakly expressed in thyroid, fetal brain, fetal lung, retina, spinal cord and bone marrow. Not expressed in testis, pancreas, adrenal gland, placenta, liver and kidney. Expressed in both differentiating and adult muscles. Ubiquitinated by FBXL22, leading to proteasomal degradation. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Silenced in MKN28 and MKN74 gastric cancer cell lines due to aberrant methylation of the gene. Belongs to the filamin family. Truncated N-terminus. Truncated N-terminus.