Many　Ser/Thr　protein　kinases,　to　be　fully　activated,　are　obligated　to　introduce　a　phospho-Ser/Thr　in　their　activation　loop.　Presently,　the　similarity　of　activation　loop　between　two　crystal　complexes,　i.e.　glycogen　synthase　kinase　3　beta　(GSK3　beta)-AMPNP　and　GSK3　beta-sulfate　ion　complex,　indicates　that　the　activation　segment　of　GSK3　beta　is　preformed　requiring　neither　a　phosphorylation　event　nor　conformational　changes.　GSK3　beta,　when　participated　in　glycogen　synthesis　and　Wnt　signaling　pathways,　possesses　a　unique　feature　with　the　preference　of　such　substrate　with　a　priming　phosphate.　Experimental　mutagenesis　proved　that　the　residue　arginine　at　amino　acid　96　mutations　to　lysine　(R96K)　or　alanine　(R96A)　selectively　abolish　activity　on　the　substrates　involved　in　glycogen　synthesis　signaling　pathway.　Based　on　two　solved　crystal　structures,　wild　type　(WT)　and　two　mutants　(R96K　and　R96A)　GSK3　beta-ATP-phospho-Serine　(pSer)　complexes　were　modeled.　Molecular　dynamics　simulations　and　energy　analysis　were　employed　to　investigate　the　effect　of　pSer　involvement　on　the　GSK3　beta　structure　in　WT,　and　the　mechanisms　of　GSK3　beta　deactivation　due　to　R96K　and　R96A　mutations.　The　results　indicate　that　the　introduction　of　pSer　to　WT　GSK3　beta　generates　a　slight　lobe　closure　on　GSK3　beta　without　any　remarkable　changes,　which　may　illuminate　the　experimental　conclusion,　whereas　the　conformations　of　GSK3　beta　and　ATP　undergo　significant　changes　in　two　mutants.　As　to　GSK3　beta,　the　affected　positions　distribute　over　activation　loop,　alpha-helix,　and　glycine-rich　loop.　Based　on　coupling　among　the　mentioned　positions,　the　allosteric　mechanisms　for　distorted　ATP　were　proposed.　Energy　decomposition　on　the　residues　of　activation　loop　identified　the　important　residues　Arg96　and　Arg180　in　anchoring　the　phosphate　group.