Hubbard, S. R., EMBO J., 1997, 16, 5572.

This crystal structure shows the activated tyrosine kinase domain of the b-chain of the insulin receptor in complex with a peptide substrate and a non-hydrolysable ATP analogue (ANP), in which the terminal P-O-P oxygen is replaced with a nitrogen atom.  Also present are Mg²⁺ (for ATP binding) and three phosphotyrosines produced by autophosphorylation.  In this case, phosphorylation produces a conformational change of the kinase that allows access of the substrate and ATP to the active site.  Phosphate is transferred directly from ATP to the substrate (ie not from the autophosphorylated tyrosines, although the phosphorylated kinase is active in the absence of substrate).  The aspartate (base) and argininine (transition state stabiliser) of the catalytic site can be seen in this structure.