IDENTIFICATION OF FUNCTIONAL DOMAINS IN AMPD1 BY MUTATIONAL ANALYSIS

AMP deaminase (AMPD) is a complex allosteric enzyme encoded by a multi gene family in higher eukaryotes. The amino terminus of each AMPD gene is unique, while the mid and carboxy termini have been highly conserv ed among all the AMPD genes. Mutational analyses of the AMPD1 gene dem onstrate that the catalytic site and a regulatory site, likely an ATP binding site, are located in the highly conserved carboxy terminus. De letion mutants and a normal splice variant of AMPD1 demonstrate that t he amino terminus has a profound influence on catalytic activity of AM PD and by inference from prior studies this region arse influences bin ding of AMPD1 to myosin. Results of these studies suggest a regulatory model in which alternative splicing in the amino terminal region of A MPD1 generates isoforms of AMPD that exhibit differential sensitivity to effector molecules such as ATP. (C) 1994 Academic Press, Inc.