DPP is regulated by the Dorsal transcription factor and secreted by dorsal cells. DPP is synthesized in an inactive form and therefore requires enzymatic proteolysis for its activation.
Proteolysis refers to the cutting up or digestion of proteins.
DPP as originally synthesized is inactive. Undergoing proteolysis allows DPP to become active. Tolloid protein contains a metalloprotease, and is therefore, a candidate for DPP proteolysis. In addition to a protease domain, TLL possesses two epidermal growth factor repeats and five copies of a repeat found in certain vertebrate complement components. Complement consists of enzymes that kill cells when activated by antibody molecules.