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A new intracellular serine protease inhibitor expressed in the rat pituitary gland complexes with granzyme B.

Hill RM, Morresey KS, Coates LC, Mezey E, Fell B, Bratt T, Trapani JA, Birch NP

  • Journal FEBS letters

  • Published 25 Jan 1999

  • Volume 440

  • ISSUE 3

  • Pagination 361-4

  • DOI 10.1016/s0014-5793(98)01475-6


We have cloned a novel serpin (raPIT5a) from a rat pituitary cDNA library which is structurally related to members of the ovalbumin subfamily of serine protease inhibitors. This new cDNA encodes a 374-amino acid protein, designated raPIT5a. raPIT5a was expressed in specific cells in the intermediate and anterior lobes of the pituitary. Recombinant raPIT5a was not secreted suggesting raPIT5a functions to inhibit intracellular proteases. Recombinant raPIT5a formed an SDS-stable complex with human granzyme B, a serine protease which induces apoptosis by activating members of the caspase enzyme family. These data suggest raPIT5a may have a role in regulating granzyme B or related enzymes and apoptosis in the pituitary gland.