If cell surface receptors can rapidly signal to the nucleus by activating latent gene regulatory proteins such as STAT's at the plasma membrane, why do most cell cell surface receptors use long, indirect signaling cascades to influence gene transcription in the nucleus?© BrainMass Inc. brainmass.com March 21, 2019, 12:28 pm ad1c9bdddf
If cell surface receptors can rapidly signal to the nucleus by activating latent gene regulatory proteins such as STAT's at the plasma membrane, why do most cell, cell surface receptors use long, indirect signaling cascades to influence gene transcription in the nucleus?
With some signal transduction systems, stimulation of the cell surface receptor by attachment of the extracellular signaling compound results in the direct activation of a protein that influences genome activity. This is the simplest system by which an extracellular signal can be transduced into a genomic response.
The direct system is used by many cytokines such as interleukins and interferons, which are extracellular signaling polypeptides that control cell growth and division. Binding of these polypeptides to their cell surface receptors results in activation of a type of transcription factor called a STAT (signal transducer and activator of transcription). Activation is by phosphorylation of a single tyrosine amino acid at a position near to the C terminus of the STAT polypeptide. If the cell surface receptor is a member of the tyrosine kinase family then it is able to activate the STAT directly. If it is a tyrosine-kinase-associated receptor then it does not itself have the ability to phosphorylate a STAT, or any other intracellular protein, but acts through intermediaries called Janus kinases (JAKs). Binding of the signaling molecule to a tyrosine-kinase-associated ...
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