How do small GTPases influence vesicle trafficking?

Small GTPases play a critical role in the regulation of vesicle trafficking by controlling key steps in the processes of vesicle budding and fusion. These GTPases function as molecular switches; they cycle between an active GTP-bound state and an inactive GDP-bound state.

In the context of vesicle trafficking, when small GTPases are activated by exchanging GDP for GTP, they can interact with specific effector proteins that are involved in the budding of vesicles from donor membranes. For instance, they can recruit coat proteins that aid in the formation of transport vesicles. Additionally, during the fusion process, small GTPases help mediate the interaction between vesicles and target membranes, promoting the fusion of the vesicle with its intended destination.

This regulatory function ensures that vesicle trafficking is precise and efficiently coordinated, facilitating the correct movement of proteins and lipids within the cell. By governing these critical steps in vesicle dynamics, small GTPases are essential for maintaining cellular organization and functionality.