Identification of ostrich and chicken cholecystokinin cDNA and intestinal peptides

The cDNAs encoding the preprohormones of the regulatory peptides cholecysto kinin (CCK) and the related gastrin have been identified in a number of ver tebrate species. However, from birds only chicken preprogastrin is known. I n the present study preproCCK cDNA was identified in two species of birds, ostrich and chicken. In addition, the molecular forms of the bioactive pept ides expressed in the small intestine were characterized. Both preproCCKs c ontain mono basic processing sites for the production of CCK-70 and -8 as s een in turtle and bullfrog. However, compared to these species an unusually large proportion was processed to the small forms CCK-7 and -8 and only mi nute amounts to larger forms. The encoded preprohormones are very similar t o each other and to turtle CCK. Furthermore, they also show a high degree o f similarity to the CCKs identified in more distant vertebrates. This confi rms that CCK is highly conserved among vertebrates while the structure of g astrin, the other member of the CCK/gastrin family, is considerably more va riable. (C) 2000 Elsevier Science Inc. All rights reserved.