OTP is a member of the homeodomain (HD) family. HD family proteins are helix-turn-helix transcription factors that play key roles in the specification of cell fates. This protein may function during brain development.This gene encodes a member of the homeodomain (HD) family. HD family proteins are helix-turn-helix transcription factors that play key roles in the specification of cell fates. This protein may function during brain development.