Enables Notch binding activity; glycosphingolipid binding activity; and receptor ligand activity. Involved in several processes, including lateral inhibition; post-embryonic animal morphogenesis; and regionalization. Located in several cellular components, including apical cortex; apical plasma membrane; and axolemma. Is expressed in several structures, including dorsal thoracic disc primordium; epithelium; gut section; imaginal disc; and organism subdivision. Used to study dilated cardiomyopathy. Human ortholog(s) of this gene implicated in Alagille syndrome; congenital heart disease (multiple); multiple sclerosis; and neuromuscular disease (multiple). Orthologous to human JAG1 (jagged canonical Notch ligand 1) and JAG2 (jagged canonical Notch ligand 2).