RAG1 subunit and contains two aspartic acid residues and one glutamic acid residue (D600, D708, and E962, respectively). This active site “DDE motif” is found in many enzymes that cleave DNA

TLS Online TPP Program

#Id: 1378

#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

#Id: 1379

#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

#Id: 1380

#Unit 4. Cell Communication and Cell Signaling

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

TLS Online TPP Program

#Id: 1381

#Unit 4. Cell Communication and Cell Signaling

At steady state, ATP–G-actin subunits add preferentially to the (+) end, while ADP–G-actin subunits disassemble from the (−) end, giving rise to treadmilling of subunits.

TLS Online TPP Program

#Id: 1382

#Unit 4. Cell Communication and Cell Signaling

Profilin enhances the exchange of ADP for ATP on G-actin. Cofilin enhances the rate of loss of ADP-actin from the filament (−) end. Thymosin-β4, binds to ATP–G-actin in such a way that it inhibits addition of the actin subunit to either end of the filament.

TLS Online TPP Program

#Id: 1383

#Unit 4. Cell Communication and Cell Signaling

Formin protein nucleate the assembly of unbranched filaments, (FH1 and FH2 domains-Actin nucleation by the formin FH2 domain).

Formins are activated by membrane-bound Rho-GTP, a Ras-related small GTPase.

The Arp2/3 Complex Nucleates Branched Filament Assembly.