Insulin Receptor Structure and Function 
real time: we can now follow the phosphoryla- 
tion of individual tyrosine residues of such pep- 
tides (especially the order of phosphorylation of 
multiple tyrosines) , as well as examine the con- 
tribution of individual amino acid residues to the 
kinetics of tyrosine phosphorylation of the pep- 
tide. Thus it should be possible to determine 
directly the stereochemical requirements and 
dynamics of efficient exogenous substrate 
phosphorylation by this tyrosine kinase. These 
studies complement efforts to obtain the three- 
dimensional structure of the enzyme through 
x-ray crystallography (in collaboration with 
Wayne Hendrickson) . 
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