[Campbell Biology P.271] Which of the following statements accurately distinguishes Receptor... | Practice Question

Which of the following statements accurately distinguishes Receptor Tyrosine Kinases RTKs from most cytoplasmic protein kinases, based on the provided text?

  • A: RTKs primarily phosphorylate serine or threonine residues, whereas cytoplasmic protein kinases phosphorylate tyrosine residues.
  • B: RTKs typically act on proteins different from themselves, while cytoplasmic protein kinases phosphorylate other RTKs in a dimer.
  • C: RTKs phosphorylate tyrosines, while most cytoplasmic protein kinases phosphorylate serine or threonine residues.
  • D: Only RTKs are involved in signal transduction pathways, whereas cytoplasmic protein kinases are involved in cell division regulation.

Explanation

The text explicitly states: 'Recall that a receptor tyrosine kinase RTK is a specific kind of protein kinase that phosphorylates tyrosines on the other RTK in a dimer. Most cytoplasmic protein kinases, however, act on proteins different from themselves. Another distinction is that most cytoplasmic protein kinases phosphorylate either of two other amino acids, serine or threonine, rather than tyrosine.' This directly supports option C.