<Li> Several proteins important for the stability of the sarcomeric structure are found in the Z - line as well as in the M - band of the sarcomere . </Li> <Li> Actin filaments and titin molecules are cross-linked in the Z - disc via the Z - line protein alpha - actinin . </Li> <Li> The M - band proteins myomesin as well as C - protein crosslink the thick filament system (myosins) and the M - band part of titin (the elastic filaments). </Li> <Li> The M - line also binds creatine kinase, which facilitates the reaction of ADP and phosphocreatine into ATP and creatine . </Li>

Arrangement of actin and myosin in cardiac muscle