span the membrane and have a hydrophilic cytosolic domain,which interacts with internal molecules, a hydrophobic membrane-spanning domain that anchors it within the cell membrane,and a hydrophilic extracellular domain that interacts with external molecules. The hydrophobic domain consists of one,multiple,or a combination of helices and sheet protein motifs.
Covalently bound to single or multiple lipid molecules hydrophobically insert into the cell membrane and anchor the protein. The protein itself is not in contact with the membrane.
Attached to integral membrane proteins,or associated with peripheral regions of the lipid bilayer.These proteins tend to have only temporary interactions with biological membranes,and once reacted,the molecule dissociates to carry on its work in the cytoplasm