Ectopeptidases

Aminopeptidase N (APN)/CD13 and dipeptidylpeptidase IV (DPIV)/CD26 are proteolytic enzymes with ubiquitous occurrence in the body of animals and men. Their physiological roles depend on the respective location: in gut and kidney tubules degradation of smaller proteins and peptides serves in absorption of nutrients or reabsorption of amino acids from urine. In the CNS their important substrates are biologically active peptides (for example, enkephalins). This book, however, has a strong focus on the role APN and DPIV play in the haematopoietic system, where again signal peptides and small proteins (cytokines) are among the most interesting substrates. Additionally, both the membrane bound peptidases play roles as partners in signal transduction of lymphocytes and monocytes, and inhibition of their enzymatic activity results in cell cycle arrest, inhibition of DNA synthesis and characteristic changes of cytokine secretion pattern of T cells. This knowledge more and more is used as the base of therapeutic strategies in the treatment of a variety of inflammatory and autoimmune diseases as well as of tumours of different origin.
The editors themselves with their colleagues have contributed important results about APN and DPIV that are reviewed here, and additionally, most of the leading groups in this field from Europe, US, Australia and Japan have contributed reviews and latest, partially unpublished results of their work.