Enables histone H3K4 methyltransferase activity. Involved in determination of adult lifespan and transdifferentiation. Located in nucleus. Expressed in several structures, including germ line; hermaphrodite distal tip cell; intestine; and nerve ring. Human ortholog(s) of this gene implicated in neurodevelopmental disorder with speech impairment and dysmorphic facies. Is an ortholog of human SETD1A (SET domain containing 1A, histone lysine methyltransferase).