A basic-HLH transcription factor, HLH54F, is highly expressed in the prothoracic gland in the silkworm Bombyx mori and the fruit fly Drosophila melanogaster.

We describe our findings on HLH54F, a basic helix-loop-helix transcription factor gene that was highly expressed in the prothoracic gland, an organ producing the insect steroid ecdysone. HLH54F was uncovered by the use of an expressed sequence tag database of the silkworm Bombyx mori. It was also highly expressed in the prothoracic gland of the fruit fly Drosophila melanogaster.