What is a key characteristic of a target protein that has a GPI-anchor?

A protein that is anchored to the cell membrane by a glycosylphosphatidylinositol (GPI) anchor typically features a C-terminal hydrophobic domain. This hydrophobic region is essential for its embedding within the lipid bilayer of the membrane. The GPI anchor itself is a glycolipid that facilitates the attachment of the protein to the membrane, allowing it to perform its functions in the cell surface.

The presence of the hydrophobic domain at the C-terminus ensures that the overall structure of the protein allows for proper orientation and stability within the membrane. This characteristic is crucial for the functionality of membrane proteins, as it influences their interactions with other membrane components and their role in cellular processes.

In contrast, the other characteristics—such as an N-terminal hydrophilic domain, hydrophilic side chains, or an acidic C-terminal region—are not defining features of proteins with GPI anchors. These features may apply to different kinds of membrane proteins or proteins with other types of membrane attachment, but they do not specifically denote the characteristic that defines a protein with a GPI anchor.