The ER captures selected proteins from the cytosol as they are being synthesized. These are of two types:

Transmembrane proteins

Water-soluble proteins

TLS Online TPP Program

#Id: 8333

#Unit 2. Cellular Organization

Jasplakinolide,

a sponge toxin, enhances nucleation by binding and stabilizing actin dimers and lowering the Cc.

TLS Online TPP Program

#Id: 8334

#Unit 2. Cellular Organization

Phalloidin 

isolated from Amanita phalloides, binds at the interface between subunits in F-actin, locking adjacent subunits together and preventing depolymerization.

TLS Online TPP Program

#Id: 8335

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 8336

#Unit 2. Cellular Organization

Actin filament treadmilling is accelerated by:

Profilin and Cofilin

TLS Online TPP Program

#Id: 8337

#Unit 2. Cellular Organization

Profilin – G-actin nucleotide exchange (ADP to ATP) 

Cofilin – F-actin disassembly

Thymosin B-4 – G-actin monomer sequestering

TLS Online TPP Program

#Id: 8338

#Unit 2. Cellular Organization

Profilin can bind proteins with sequences rich in proline residues at the same time it is bound to actin.