Transmembrane proteins
Transmembrane proteins are proteins which are situated on the lipid membrane of cells. They have transmembrane spanning regions which pass through the lipid bilayer of the cell membranes any number of times depending on the protein in question. There are multiple families of transmembrane proteins and each protein has a specific role.
These proteins are normal highly structured as the amino acid primary protein sequence allows for the formation of alpha-helices or beta-sheets.