The C5b component is extremely labile, is not covalently bound to the membrane like C3b and C4b, and is rapidly inactivated unless it is stabilized by the binding of C6.

TLS Online TPP Program

#Id: 1392

#Unit 4. Cell Communication and Cell Signaling

The giant protein titin extends through the thick filaments and attaches to the Z disk.

TLS Online TPP Program

#Id: 1393

#Unit 4. Cell Communication and Cell Signaling

Nebulin binds actin subunits and determines the length of the thin filament.

TLS Online TPP Program

#Id: 1394

#Unit 4. Cell Communication and Cell Signaling

CapZ blocks the (+) end, which is where filaments normally grow, so its function is to limit actin dynamics to the (−) end.

TLS Online TPP Program

#Id: 1395

#Unit 4. Cell Communication and Cell Signaling

Tropomodulin blocks (−) ends, where filament disassembly normally occurs; thus the major function of tropomodulin is to stabilize filaments .

TLS Online TPP Program

#Id: 1396

#Unit 4. Cell Communication and Cell Signaling

All small GTPases of the Ras superfamily, Cdc42, Rac, and Rho act as molecular switches, inactive in the GDP-bound state and active in the GTP-bound state.

TLS Online TPP Program

#Id: 1397

#Unit 4. Cell Communication and Cell Signaling

Actin-based motors powered by ATP hydrolysis.