Oligomerization-induced modulation of TPR-MET tyrosine kinase activity.

摘要: Abstract Phosphorylation, although necessary, may not be sufficient to fully activate many receptor tyrosine kinases (RTKs). Oligomerization-induced conformational changes necessary modulate the kinetic properties of RTKs and render them functional. To investigate this regulatory mechanism, recombinant TPR-MET, a functionally active oncoprotein derivative RTK c-MET, has been expressed purified for quantitative enzymatic analysis. This naturally occurring contains cytoplasmic domain c-MET fused coiled coil motif from nuclear pore complex (TPR). cytoMET, monomeric analog also comparative ATP peptide substrates have kinetically characterized both TPR-MET cytoMET. Significantly, phosphorylated smaller Km values (Km,ATP) (Km,peptide) larger kcat relative provides first direct evidence that oligomerization simply activation loop phosphorylation modulates activity. The dissociation constants (Kd,ATP) two enzymes displayed significant differences. In contrast, KI competitive inhibitor staurosporin are similar enzymes. These results suggest much oligomerization-induced occur with respect substrate binding or catalytic efficiency. possibility within implications structure-based design inhibitors development detailed mechanistic model activation.