Editing Integral membrane protein (section)

===Integral polytopic protein===
{{Main|Transmembrane protein}}
The most common type of IMP is the [[transmembrane protein]], which spans the entire [[biological membrane]]. [[Single-pass membrane protein]]s cross the membrane only once, while '''multi-pass''' membrane proteins weave in and out, crossing the membrane several times. Single pass membrane proteins can be categorized as Type I, which are positioned such that their carboxyl-terminus is towards the [[cytosol]], or Type II, which have their amino-terminus towards the cytosol. Type III proteins have multiple transmembrane domains in a single polypeptide, while type IV consists of several different polypeptides assembled together in a channel through the membrane. Type V proteins are anchored to the lipid bilayer through covalently linked lipids. Finally Type VI proteins have both transmembrane domains and lipid anchors.<ref>Nelson, D. L., & Cox, M. M. (2008). ''Principles of Biochemistry'' (5th ed., p. 377). New York, NY: W.H. Freeman and Company.</ref>