| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2201160 | Neurochemistry International | 2011 | 10 Pages |
The levels of expression of Gsα(short and long), Gαolf and Gβ(common) subunits, and calcium-sensitive adenylyl cyclases isoforms (AC1, 5/6, and 8) in human brain cortical and caudate membranes were quantified by western blot analysis in order to establish their contribution to the patterns of AC functioning. Both areas expressed Gsαlong (52 kDa) with values ranging from about 1400 ng/mg of membrane protein in cerebral cortex to close to 600 ng/mg of membrane protein in caudate nucleus. In contrast, Gsαshort and Gsαolf were expressed separately, Gsαshort in cortical membranes with values around 500 ng/mg of membrane protein and Gαolf in caudate membranes with values around 1300 ng/mg of membrane protein. Quantitative measurements of Gβ, revealed a similar expression level in cortical and caudate membranes (5444 ± 732 versus 5511 ± 394 ng/mg protein; p = 0.966). The Bmax values of GTPγS-dependent [3H]-forskolin binding show the following descending order: rat striatal membranes > rat cortical membranes = human caudate membranes > human cortical membranes. Therefore, as measured immunochemically and by [3H]-forskolin binding, there seems to be a vast excess of Gsα subunits over catalytic units of AC. The highest levels of AC5/6 expression were detected in caudate membranes. AC8 was little expressed, and there were no significant differences in the relative values between both human brain regions. Finally, the levels of the AC1 isoform were significantly lower in caudate than in cortical membranes. It is concluded that these stoichiometric data contribute nonetheless to explain the significant differences observed in signalling capacities through the AC system in both human brain regions.
Research highlights▶ The stoichiometry has been completed for the Gs-linked AC pathway in human brain. ▶ There is a substantial molar excess of Gsα subunits relative to AC levels. ▶ AC is identified as the most critical component in determining efficacy of the system.
