Thick filament-associated protein located in the crossbridge region of vertebrate striated muscle a bands. Slow skeletal protein that binds to both myosin and actin (PubMed:31264822, PubMed:31025394). In vitro, binds to native thin filaments and modifies the activity of actin-activated myosin ATPase. May modulate muscle contraction or may play a more structural role. Interacts with USP25 (isoform USP25m only); the interaction prevents proteasomal degradation of MYBPC1. 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. Belongs to the immunoglobulin superfamily. MyBP family.