A protein comprising at least one hybdrophobic domain which attaches/anchors within the lipid bilayer of an animal cell. A chanel protein is a special case of a membrane protein.

Many membrane proteins comprise at least one alpha helice domain enabling a protein to anchor into an animal cellular membrane. The 'anchor' can extensively 'spiral' in and out of the membrane, often supporting hydrophilic domains. The hydrophilic domains may exist within the cytoplasm side of the cell membrane or the external face, e.g. cellular receptors. Pathogens regularly deploy membrane proteins to anchor their B-cell antigenic domains into the pathogen lipid-bilayer as the method to attack the hosts cellular receptor.