Autophosphorylation of soluble insulin receptor protein-tyrosine kinases. super(1)H NMR spectral changes observed during phosphorylation of mobile tyrosine residues

Autophosphorylation of a soluble similar to 48-kDa derivative of the insulin receptor protein-tyrosine kinase occurs at multiple tyrosine residues (analogous to tyrosines 1158, 1162, and 1163 in the kinase homology region of the native receptor and tyrosines 1328 and 1334 in the carboxyl-terminal tail) and is accompanied by an increase in the specific activity of the enzyme toward exogenous substrates. A comparison of super(1)H NMR spectra of similar to 48- and similar to 38-kDa forms of enzyme (the latter generated by tryptic deletion of similar to 10 kDa from the carboxyl terminus of the similar to 48-kDa protein) allows a correlation of observed mobile tyrosine resonances to two of the known sites of autophosphorylation (residues 1328 and 1334).