AP BIOLOGY

Detailed explanation-1: -Tyrosine kinases are important mediators of the signaling cascade, determining key roles in diverse biological processes like growth, differentiation, metabolism and apoptosis in response to external and internal stimuli. Recent advances have implicated the role of tyrosine kinases in the pathophysiology of cancer.

Detailed explanation-2: -Protein kinases are enzymes that catalyze the transfer of the -phosphate of ATP to the protein substrates, thus altering their functions.

Detailed explanation-3: -Protein tyrosine kinases catalyze the transfer of the -phosphoryl group of ATP to proteins on tyrosine residues (Figure 1). These enzymes are critical for cell signal transduction in a variety of physiologic contexts.

Detailed explanation-4: -Phosphorylation of the catalytic domain of the RTKs activates and increases the activity of the kinase domain, whereas the non-catalytic domains create various anchoring sites for cytoplasmic targets involved in intracellular signal transduction.