Myosin-binding protein which plays a role in cardiac function (PubMed:28778945). Seems to regulate conduction in the atria and ventricular conduction systems (PubMed:28778945). Expressed in heart, with higher expression in the atria. Expressed in left atrium and ventricle, arteria mammaria interna and skeletal muscle. Expressed specifically en the left atrium. Belongs to the immunoglobulin superfamily. MyBP family.