Tissue distribution of a novel neurotensin-degrading metallopeptidase. An immunological approach using monospecific polyclonal antibodies.

A monospecific polyclonal antiserum was raised against a recently purified rat brain neurotensin-degrading metallopeptidase. The purified IgG fraction immunoprecipitated the peptidase and inhibited its proteolytic activity. Western blot analyses revealed that the immune fraction recognizes only one protein in rat brain homogenates, and this corresponds closely to the purified enzyme. The IgG displayed a restricted specificity towards the peptidase from murine origin. In the rat, the neurotensin-degrading enzyme was widely distributed throughout peripheral organs with the noticeable exception of the duodenum. In addition, the peptidase was detected in various cell lines or membrane preparations of neural or extraneural origin in which it had been previously characterized by means of biochemical methods. In light of this widespread distribution, the putative role of the peptidase in the metabolism of neuropeptides is discussed.