May play a role during maturation and/or organization of muscles cells. Interacts with beta-1 integrin subunit. This interaction is regulated by divalent cations, and it occurs only in absence of calcium. Expressed in skeletal and cardiac muscles but not in other tissues. The tail domain binds to the cytoplasmic domain of both integrin beta-1a and beta-1d isoforms. The presence of Ca(2+) ions does not prevent binding of a fragment consisting of the second cysteine rich repeat and the tail domain but prevents the binding of the full-length protein.