Hydrolytic and non - hydrolytic interactions in the atp regulation
of cftr- cl conductance.
Reddy, M. M., and P. M. Quinton.
Division of Biomedical Sciences, Univ. of California, Riverside,
Riverside, CA- 92521
APStracts 3:0002C, 1996.
Previously we showed in the native sweat duct that in the presence of
0.1-0.5 mM ATP, non hydrolyzable ATP analog AMP-PNP can activate
CFTR-GCl (15). The objective of this study is to determine if a.) non
hydrolytic ATP binding alone can activate CFTR- GCl after stable
phosphorylation (in the presence of ATP-[gamma]-S and phosphatase
inhibition cocktail, PIC) of CFTR or b.) an ATP hydrolysis (in
addition to phosphorylation) is required to support subsequent non
hydrolytic ATP regulation of CFTR-GCl. We show that stably
phosphorylated CFTR could only be activated by AMP-PNP in the
presence of a small background [ATP]. However, AMP-PNP can sustain
previously activated CFTR-GCl in the absence of ATP. Even though Mg2+
is required for phosphorylation activation of CFTR-GCl. However, once
stably phosphorylated, ATP activation of CFTR- GCl is independent of
Mg2+. Our results show that both hydrolytic and non-hydrolytic
interactions regulate CFTR-GCl in vivo. Non-hydrolytic ATP
interaction plays a significant role in both activation and
deactivation of CFTR-GCl.
Received 25 July 1995; accepted in final form 13 December 1995.
APS Manuscript Number C454-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96