Atypical type III intermediate filament (IF) protein that may play a supportive role in the efficient coupling of mechanical stress between the myofibril and fiber exterior. May facilitate lateral force transmission during skeletal muscle contraction. Does not form homofilaments nor heterofilaments with other IF proteins. May link the dystrophin-associated glycoprotein complex (DAPC) to intracellular desmin (DES) filaments. Interacts with DES and DTNA. In skeletal muscle, colocalizes with DES and DTNA, and is localized at the myotendinous and neuromuscular junctions, sarcolemma and Z-lines. In myotubes, detected in a punctate cytoplasmic pattern. Detected strongly in skeletal muscle and heart and weakly in lung (at protein level). Highly expressed in skeletal muscle and lung and weakly in lung and testis. Up-regulated in dystrophic muscle (at protein level). Displays no obvious abnormalities, have a reduced capacity to generate force during isometric contractions in skeletal muscle. Belongs to the intermediate filament family.