Biosynthesis and cell surface delivery of the nhe1 isoform of na+/
h+ exchanger in a6 cells.
Coupaye-Gerard, Brigitte, Cresence Bookstein, Pamela Duncan, Xi Yin
Chen, Peter R. Smith, Mark Musch, Stephen A. Ernst, Eugene B. Chang,
and Thomas R. Kleyman.
Departments of Medicine and Physiology, University of Pennsylvania
and VA Medical Center, Philadelphia, PA; the Department of Medicine,
University of Chicago, Chicago, IL; the Department of Physiology,
Medical College of Pennsylvania and Hahnemann University,
Philadelphia, PA; and Department of Anatomy and Cell Biology,
University of Michigan, Ann Arbor, MI 48109
APStracts 3:0173C, 1996.
The Na+/H+ exchanger NHE1 isoform is localized to the basolateral
membrane of renal and intestinal epithelia. We examined the plasma
membrane distribution, biosynthesis, and cell surface delivery of
NHE1 in A6 epithelia. NHE1 was localized to the basolateral membrane.
Studies of NHE1 biosynthesis with a pulse-chase protocol demonstrated
that a core glycosylated, endoglycosidase H-sensitive, 90 kDa NHE1
was present 0 to 5 hours into the chase period, and that mature 110
kDa NHE1 was present 1 to 24 hours into the chase period. Studies of
plasma membrane delivery of newly synthesized NHE1 demonstrated that
the 90 kDa NHE1 was detected at both apical and basolateral membranes
2 to 5 hours into the chase period. The 110 kDa NHE1 was observed at
the basolateral membrane 5 to 24 hours into the chase period. These
results suggest that NHE1 is expressed primarily at the basolateral
membrane of A6 cells; that core glycosylated NHE1 is delivered to the
plasma membrane in a nonpolarized manner; and that mature 110 kDa
NHE1 is delivered to the basolateral membrane.
Received 4 April 1996; accepted in final form 15 May 1996.
APS Manuscript Number C189-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96