Cloning and induction by low nacl intake of avian intestine na+
channel subunits.
Goldstein, Orly, Carol Asher, and Haim Garty.
Dept. of Membrane Research and Biophysics, The Weizmann Institute
of Science, Rehovot 76100, Israel
APStracts 3:0265C, 1996.
The [alpha] subunit of the highly Na+ selective amiloride blockable
channel (ENaC) was cloned from chicken lower intestine. The deduced
amino-acid sequence of the avian clone exhibits [sim]60% identity to
the previously cloned mammalian and amphibian [alpha] subunits. It
also maintains the same hydropathy profile and structural motifs.
These include: two transmembrane domains separated by a large
extracellular loop, four extracellular N-glycosylation sites, a
cystein rich box in the extracellular domain, and a proline rich
stretch at the carboxy terminal. Xenopus oocytes injected with cRNA
transcribed from this clone, express a small amiloride-blockable Na+
conductance. Degenerate primers have been used to amplify two other
related products. Sequence homology indicates that one of them is the
[beta] subunit while the other appears to represent a closely related
but different transcript. Regulation of the mRNA corresponding to
these clones was examined in chickens fed normal and low NaCl
rations. The low salt diet evoked a 4 fold increase in the abundance
of mRNA coding for the [alpha] subunit, presumably through an
increase in plasma aldosterone. The [beta] and O[beta]-likeO
transcripts were even more strongly affected. The current data
provide additional information on sequence conservation in the
growing ENaC family and demonstrate that the avian intestine channel
is strongly induced by varying NaCl intake.
Received 19 January 1996; accepted in final form 16 July 1996.
APS Manuscript Number C31-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996