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Integral polytopic protein
The most common type of IMP is the transmembrane protein (TM), which spans the entire biological membrane. Single-pass membrane proteins cross the membrane only once, while multi-pass membrane proteins weave in and out, crossing several times. Single pass TM 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.

Integral monotopic proteins
Integral monotopic proteins are associated with the membrane from one side but do not span the lipid bilayer completely.

Determination of protein structure
The Protein Structure Initiative (PSI), funded by the U.S. National Institute of General Medical Sciences (NIGMS), part of the National Institutes of Health (NIH), has among its aim to determine three-dimensional protein structures and to develop techniques for use in structural biology, including for membrane proteins. Homology modeling can be used to construct an atomic-resolution model of the "target" integral protein from its amino acid sequence and an experimental three-dimensional structure of a related homologous protein. This procedure has been extensively used for ligand-G protein–coupled receptors (GPCR) and their complexes.