Table I.

Effects of Free Mg²⁺ Ions on Nonactivated PhK

Phk	Effect	References
Kinase Activity
6.8	Time-dependent activation prior to assaya	3
6.8	Time-dependent activation prior to assay when incubated with phosphorylasea	4
6.8	Stimulates when in excess over MgATP	5,6
8.2	Stimulates when in excess over MgATP	6,7
Affinity for Interacting Molecules
6.8	Alters affinity for Ca2+ plus induces new Ca2+ binding sites	8
7.5	Increases affinity for glycogen phosphorylase	9
Effects on Specific Subunits
8.2	Increased ββ1 and αγ conjugates and decreased βγγ in crosslinking by 4-phenyl-1,2,4-triazoline-3,5-dione	10
6.8	Protects β subunit from trypsinolysis	11
6.8	Increased binding of mAb γ79 to free γ subunit and to PhK	12
6.8	Increased binding of mAb γ88 and mAb γ to PhK	13
6.8	Increased phosphorylation of α subunit at high [Mg2+] by two distinct protein kinases	14,15
Synergistic Effects in Concert with Ca2+ Ions
6.8	Promotes self-association of PhK	16–18
6.8	Incubation prior to assays activates kinase	19
6.8	Promotes formation of β-β dimers in crosslinking by 1,5-difluoro-2,4-dinitrobenzene (DFDNB)	20
6.8	Incubation prior to assays induces an EGTA- insensitive activity	21
6.8/7.0	Enhances binding to glycogen	22–24

^aWithout divalent cation chelator.