Type II Transmembrane Proteins

The Fas ligand or FasL is a type II transmembrane protein that belongs to the tumor necrosis factor (TNF) family. The binding of Fas ligand with its receptor induces apoptosis. 

Cell membrane spanning proteins contain a luminal/ extracellular domain, a transmembrane region and a cytosolic domain. In a type II transmembrane protein the C-terminus is the extracellular/luminal part of the protein, whereas the N-terminus comprises the cytosolic region of the membrane protein. 

Figure 46-5. Variations in the way in which proteins are inserted into membranes. This schematic representation, which illustrates a number of possible orientations, shows the segments of the proteins within the membrane as a-helicesand the other segments as lines. The LDL receptor, which crosses the membrane once and has its amino terminal on the exterior, is called a type I transmembrane protein. The asialoglycoprotein receptor, which also crosses the membrane once but has its carboxyl terminal on the exterior, is called a type II transmembrane protein. The various transporters indicated (eg, glucose) cross the membrane a number of times and are called type III transmembrane proteins they are also referred to as polytopic membrane proteins. (N, amino terminal C, carboxyl terminal.) (Adapted, with permission, from Wickner WT, Lodish HF Multiple mechanisms of protein insertion into and across membranes. Science 1985 230 400. Copyright 1985 by the American Association for the Advancement of Science.)...

This finding is particularly interesting as it suggests most or all NETs are type II transmembrane proteins. 

---