Question

Where would you expect to find the Ca₂₊ activated form of gelsolin in cells crawling by amoeboid movement?

A) in and around focal adhesions
B) at a pseudopodium tip where endoplasm is converting to ectoplasm
C) at a pseudopodium base where ectoplasm is converting to endoplasm
D) in the primary cilium
E) at the cell trailing edge where force is produced to drive endoplasm forward streaming

Answer 1

You would expect to find the Ca₂⁺ activated form of gelsolin at the tip of a pseudopodium, where endoplasm converts to ectoplasm, as this is where actin remodeling occurs, facilitating amoeboid movement.

Step-by-step explanation:

The Ca₂⁺ activated form of gelsolin is expected to be found at a pseudopodium tip where endoplasm is converting to ectoplasm. This is because gelsolin is an actin-binding protein that helps in the regulation of actin filament assembly and disassembly, playing a key role in the amoeboid movement of cells. The actin cytoskeleton, with the assistance of gelsolin, undergoes polymerization at the leading edge of the cell to extend the pseudopodia and depolymerization at the rear, enabling cell motility. As ectoplasm is the gel-like outer layer of the cytoplasm that helps in maintaining the shape of a pseudo­podium, its formation from endoplasm at the tip suggests the area where actin remodeling is actively taking place, thus indicating the presence of the activated form of gelsolin in this region.