G(s alpha) contains an unidentified covalent modification that increases its affinity for adenylyl cyclase

Many G protein a subunits are dually acylated with myristate and palmitate or are palmitoylated on more than one cysteine residue near their N termini, The G(alpha) protein that activates adenylyl cyclase, alpha(s), is not myristoylated but can be reversibly palmitoylated. It appears that alpha(s) contains 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. Palmitoylation of native alpha(s) does not account for its high affinity for adenylyl cyclase.