Biochemical requirements for suppressing a constitutively active allele of Gs alpha

Abstract

Inappropriate activation of the Gs alpha subunit by mutation of modification of Arg201 is associated with the human diseases of McCune‐Albright Syndrome and cholera. Previous work in our laboratory identified Asp223 as a site where substitution to valine could reverse the constitutive activity of an Arg201His mutation. In this study, Asp223 was substituted with a variety of other amino acids, including glutamic acid, asparagine, glutamine, alanine, leucine, and glycine. HEK cells transfected with plasmids carrying the different Gs alpha subunit alleles were used to measure basal levels of cAMP. The Arg201His allele significantly elevates basal cAMP. Substitution of Asp223 with nonpolar residues suppressed the elevation in basal cAMP, while substitution with acidic or polar residues had no effect on the constitutive activity of the Arg201His mutation. This characterization of which amino acids at residue 223 can suppress the Arg201His mutation may provide a foundation for identifying small molecules that can be used as effective therapies against McCune‐Albirght Syndrome.Supported by NIH grant1R15DE02109‐01