Identification of ethanol responsive domains of adenylyl cyclase.
BACKGROUND
The activity of adenylyl cyclase (AC) is enhanced by pharmacologically relevant concentrations of ethanol. The enhancing effect of ethanol on AC activity is AC isoform-specific. Therefore, we hypothesized that within a cyclic AMP-generating system, AC is the target of ethanol's action and that ethanol-sensitive AC molecules contain structural elements modulated by ethanol. The structural elements are designated as "ethanol responsive domains."


METHODS
By using a series of chimeric mutants, we searched regions of the AC molecule that are important for the ethanol effect. These chimeric mutants were derived from 3 isoforms of AC: AC7 (type 7), the most ethanol responsive isoform; AC3 (type 3), an isoform that is far less responsive to ethanol; and AC2 (type 2), an isoform that is homologous to AC7 but less responsive to ethanol.


RESULTS
We identified 2 discrete regions of the AC molecule that are important for the enhancement of AC activity by ethanol. The first is the N-terminal 28-amino-acid (aa) region of the C(1a) domain. The second is the C-terminal region ( approximately 140 aa) of the AC molecule. Sequence differences in the N-terminal tail, 2 putative transmembrane domains, and the C(1b) domain are not important for ethanol's effect.


CONCLUSIONS
The current study with mammalian ACs provides a new class of alcohol-responsive protein and possibly a new mechanism of alcohol action on cellular function. The identification of ethanol responsive domains will facilitate the elucidation of the mechanisms by which ethanol enhances the activity of AC.
Yoshimura
Masami
M
Department of Pharmacology, University of Colorado Health Sciences Center, Aurora, CO, USA. myoshimura@vetmed.lsu.edu
Pearson
Susan
S
Kadota
Yoichi
Y
Gonzalez
Cristina E
CE
D000262:Adenylyl Cyclases / Q000187:drug effects* / Q000235:genetics; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000187:drug effects / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050506:Mutant Chimeric Proteins / Q000235:genetics; D009154:Mutation; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
D002492:Central Nervous System Depressants; D018076:DNA, Complementary; D007527:Isoenzymes; D050506:Mutant Chimeric Proteins; D000431:Ethanol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases