The expression and developmental regulation of the α and β subunits of the guanine nucleotide binding regulatory proteins, G(i) and G(o), were examined in rat atria and ventricles. Protein levels were determined by quantitative immunoblot analysis using affinity purified monospecific antibodies. Northern blot and dot blot analyses were used to characterize and quantitate relative amounts of mRNA encoding these G protein subunits. The concentrations of G(o)α, G(i)α and β subunit protein were found to be greater in adult atrial than in adult ventricular membranes (5.2-, 1.5-, and 2.8-fold, respectively). A corresponding 3.4-fold difference in G(o)α mRNA level was also observed, as well as a 1.3-fold difference in G(i)α-3 mRNA level. No difference was seen between the amount of β, G(i)α-1, G(i)α-2 mRNA in adult atria and adult ventricles. Comparison of neonatal and adult tissues revealed a developmental decrease in ventricular G(i)α protein and G(i)α-2 mRNA levels (70 and 47%, respectively). Developmental decreases were also observed in the amount of mRNA encoding β and G(o)α in ventricles (47 and 61%, respectively), and β and G(i)α-2 in atria (40 and 36%, respectively), while a developmental increase in atrial G(i)α-3 mRNA levels was observed (57%). These results demonstrate differences in the expression of G protein subunits in rat atria and ventricles, as well as regulation of the levels of these subunits during cardiac development.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Biological Chemistry|
|State||Published - Jan 1 1988|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology