A modification of the agglutination reaction, called agglutination inhibition, provides a highly sensitive assay for small quantities of an antigen. For example, one of the early types of home pregnancy test kits included latex particles coated with human chorionic gonadotropin (HCG) and antibody to HCG. 

TLS Online TPP Program

#Id: 8341

#Unit 2. Cellular Organization

Two major classes of actin-nucleating proteins:

1. Formins nucleate the assembly of unbranched filaments 

2. Arp2/3 complex nucleates the assembly of branched actin networks

TLS Online TPP Program

#Id: 8342

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 8343

#Unit 2. Cellular Organization

formin family members have two adjacent domains:

FH1- rich in proline, landing site for profilin–ATP–G-actin

FH2 - form a dimer and nucleate filament assembly

TLS Online TPP Program

#Id: 8345

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 8346

#Unit 2. Cellular Organization

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

TLS Online TPP Program

#Id: 8347

#Unit 2. Cellular Organization

To nucleate the assembly of branched actin filaments, Arp2/3 needs to be activated by a nucleation promoting factor (NPF)