A signaling assembly for a door leaf of an access door to a transport vehicle, including a seal that has an attaching region intended to be received at least partially in the housing of a profile of the door leaf, as well as a lighting region, and means of lighting, able to illuminate the lighting region of the seal, in such a way as to emit at least one visual signal, in particular representative of the opened and/or closed state of the door. The assembly includes a locking key received at least partially in an interior volume of the seal, with the key being able to prevent a pulling off of the seal outside the profile along a transversal direction, in reference to the main direction of the seal, the means of lighting being fixed on the locking key.