Enables activin binding activity; transforming growth factor beta binding activity; and transmembrane receptor protein serine/threonine kinase activity. Involved in heart development; positive regulation of epithelial to mesenchymal transition involved in endocardial cushion formation; and positive regulation of nitrogen compound metabolic process. Acts upstream of or within several processes, including chordate embryonic development; circulatory system development; and gastrulation. Located in apical part of cell. Is integral component of plasma membrane. Is expressed in several structures, including alimentary system; brain; limb; male reproductive gland or organ; and sensory organ. Used to study fibrodysplasia ossificans progressiva. Human ortholog(s) of this gene implicated in fibrodysplasia ossificans progressiva. Orthologous to human ACVR1 (activin A receptor type 1). [provided by Alliance of Genome Resources, Apr 2022]