1 A) Which of the following is NOT a common feature between receptor tyrosine ki

ID: 262742 • Letter: 1

Question

1 A) Which of the following is NOT a common feature between receptor tyrosine kinase signaling and cytokine receptor signaling?

Phosphotyrosine phosphatases are the primary method of downregulation of both signaling types.

The receptor is phosphorylated on multiple tyrosine residues upon activation.

Dimerization of both receptor types is required for kinase activation.

Both activate a tyrosine kinase that phosphorylates downstream targets.

1 B) Which of the following statements regarding Epo signaling is FALSE?

Phosphorylated STAT proteins dimerize and activate transcription due to conformational changes that expose nuclear localization signals.

Epo production and release by kidney cells is an example of endocrine signaling.

A dominant negative mutation in JAK2 blocks Epo signaling even in cells expressing the wild-type receptor due to receptor dimerization.

The Epo receptor exists as a monomer in the absence of ligand and dimerizes upon Epo binding.

1. Answer is

The receptor is phosphorylated on multiple tyrosine residues upon activation

But in fact cytokine receptors does not possess intrinsic tyrosine kinase activity

2. Answer is.

The Epo receptor exists as a monomer in the absence of ligand and dimerizes upon Epo binding.

In fact Epo receptor pre exists as dimer and upon ligand binding it gets homodimerization.

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