Is the Buddha nature nothingness or the Dharmakaya? In a lot of Buddhist literature you will find passages suggesting that our Buddha nature is actually "nothingness" or "emptiness". I was wondering if this was true? I'm starting to doubt this claim because of the Dharmakaya. The Dharmakaya is one of the three bodies of Buddha which is transcendent. While some say that the Dharmakaya "is" nothingness, others claim that it is neither part of space (emptiness and form) nor time. The idea is that everything, including nothingness (emptiness), originated out of the Dharmakaya. It's an impersonal force which holds everything together, originated everything, and maintains everything through a transcendent state. 

My question: What is the proper understanding of the Dharmakaya and it's relationship with our Buddha nature? Is it the Buddha nature or not?
According to Yogacara, buddha nature is a seed in the mind basis of all. According to Madhyamika, buddha nature is the emptiness of the mind of a sentient being. It is not the dharmakaya.

Dharmakaya is divided into two (sometimes three): 1. the wisdom truth body, which is the omniscient mind of a buddha, and 2. the nature truth body, which is the emptiness of the mind of a buddha. We also call the nature truth body: 'emptiness [of the mind] without defilements' while buddha nature  is 'the emptiness [of a mind with] defilements'. Just like the emptiness of the table is not the same phenomena as the emptiness of the cup, the emptiness of the mind of a sentient being (i.e. a non-buddha) is not the same as the emptiness of the omniscient mind of a buddha. Therefore, we can not say that buddha nature is the dharmakaya or that an arya buddha possesses buddha nature.

Moreover, in no traditional text have I seen the dharmakaya qualified as 'transcendent'.