SNARE-mediated fusion occurs during exocytosis of secreted proteins. In this case, 

v-SNARE, are VAMP 

t-SNAREs are syntaxin & SNAP-25

TLS Online TPP Program

#Id: 8322

#Section 3: Genetics, Cellular and Molecular Biology

Steady-state phase

G-actin monomers exchange with subunits at the filament ends, but there is no net change in the total length of filaments.

TLS Online TPP Program

#Id: 8321

#Section 3: Genetics, Cellular and Molecular Biology

Elongation phase

short oligomer rapidly increases in length by the addition of actin monomers to both of its ends, causing filament elongation

TLS Online TPP Program

#Id: 8320

#Section 3: Genetics, Cellular and Molecular Biology

The lag phase can be reduced or abolished entirely by adding premade nuclei.

TLS Online TPP Program

#Id: 8319

#Section 3: Genetics, Cellular and Molecular Biology

Nucleation phase 

Lag period (Time taken for nucleation) Rate-limiting Step.

TLS Online TPP Program

#Id: 8318

#Section 3: Genetics, Cellular and Molecular Biology

Nucleation phase 

Two G-actin molecules bind relatively weakly to each other, but addition of a third actin monomer to form a trimer makes the entire group more stable, acts as a nucleus for polymerization.

TLS Online TPP Program

#Id: 8317

#Section 3: Genetics, Cellular and Molecular Biology

Actin polymerization in vitro proceeds in three steps:

1.Nucleation phase

2.Elongation phase

3.Steady-state