When a genome contains a cluster of genes with related sequences, mispairing between nonallelic loci can cause unequal crossing over. This produces a deletion in one recombinant chromosome and a corresponding duplication in the other.

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#Unit 2. Cellular Organization

One NPF is called WASp, as it is defective in patients with Wiskott-Aldrich syndrome.

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#Unit 2. Cellular Organization

WASp activation requires two signals (This type of two-signal input, called coincidence detection):

1. regulatory phospholipid PIP2

2. small GTP-binding protein Cdc42

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#Unit 2. Cellular Organization

A second NPF is a large protein complex called WAVE

and requires small GTP-binding protein Rac1.

TLS Online TPP Program

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#Unit 2. Cellular Organization

Listeria is a food-borne bacterial pathogen has on its surface a protein ActA, which mimics an NPF that efficiently activates the Arp2/3 complex.

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#Unit 2. Cellular Organization

ActA protein binds the host protein VASP, which enhance actin assembly and confine it to the rear of the bacterium.

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#Unit 2. Cellular Organization

VASP 

has a proline-rich

hold onto the end of the newly formed filament

protect the end of the growing filament from CapZ