G_sα contains an unidentified covalent modification that increases its affinity for adenylyl cyclase

摘要

Many G protein subunits are dually acy- lated with myristate and palmitate or are palmitoylated on more than one cysteine residue near their N termini. The G_α protein that activates adenylyl cyclase, α _s, is not myristoylated but can be reversibly palmitoylated. It appears that α_s con- tains another, as-yet-unidentified covalent modification that decreases its apparent dissociation constant for adenylyl cyclase from 50 nM to <0.5 nM. This modification is at or near the N terminus of the protein and is hydrophobic. Palmitoyl- ation of native α_s does not account for its high affinity for adenylyl cyclase.