BIOL 2021 Chapter Notes - Chapter 2.6: Alpha Helix, Golgi Apparatus, Protein Structure
2 Apr 2018
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Document Summary
Most transmembrane proteins cross the membrane in an alpha helical. Sence of water, hydrogen bonding is maximized, meaning that alpha helices usually span the entire membrane before changing direction: occurs because a turn involves a loss of h bonds. Alpha helix and beta barrels are asymmetric across the membrane ey will always be found in the same, unique, orientation and on one specific side of the membrane. Asymmetry is created when the protein is synthesized in the endoplasmic reticulum. If it crosses the membrane, it has to have hydrophobic amino acids within the alpha. Acids may be within the helix and are crucial to the functioning of the protein: okay because there are so many other hydrophobic ones within the helix. Beta sheet polypeptides can be rolled into a barrel and are usually porin proteins that can transport molecules. Tend to be located in bacteria, mitochondria and chloroplasts. Tend to be a rigid structure and don"t undergo conformational changes.
