The DnaG primase is an RNA polymerase is smaller than RNA Polymerase; and synthesizes short stretches of RNA that are used as primers for DNA synthesis.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

STAT5 becomes activated in erythroid progenitor cells,  induces expression of the protein Bcl-xL.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Two mechanisms for terminating cytokine signal transduction

1.  Short-term regulation

2.  Long-term regulation

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Short-term regulation: 

JAK2 deactivation by SHP1 phosphatase

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Long-term regulation: 

• SOCS proteins

• Targets the receptor as well as JAK2 for degradation by the ubiquitin-proteasome pathway

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

The rate-limiting step in actin filament assembly is the formation of a short actin oligomer (nucleus).

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

The critical concentration (Cc) is the concentration of free G-actin at which the filaments are formed.