There are two types of channel proteins depending on their function in the cell: 

Non-gated channel proteins: These channel proteins remain open all the time, offering unhindered passage to ions and water through the cell membrane without any resistance. Non-gated channel proteins are less common as they are unable to sufficiently regulate what substances pass through the membrane. 

Gated channel proteins: These channel proteins remain closed at all times. They open to allow substances to pass through the cell membrane only after receiving specific stimuli from the environment.