Читать книгу Neurobiology For Dummies - Frank Amthor - Страница 66

Membrane proteins have a three-dimensional configuration. One end of the protein is either in the intracellular or extracellular fluid, the transmembrane region resides within the phospholipid membrane, and the protein terminal, like the beginning, is either in the intracellular or extracellular fluid. Most membrane protein subunits make multiple loops that are embedded in the membrane.

One important chemical distinction among the amino acids that make up proteins is whether the parts of the amino acid jutting out from the polypeptide chain (residues) are charged (hydrophilic or lipophobic), or relatively neutral (hydrophobic or lipophilic). The two ends of membrane proteins not embedded in the phospholipid bilayer are typically dominated by hydrophilic residues, while the portions of the protein embedded in the phospholipid bilayer are typically dominated by lipophilic residues.