Biochemistry 3381A Chapter 6.4, 10.2: Proteins 10
9 Oct 2017
School
Department
Course
Professor
Document Summary
Peripheral proteins: globular proteins that interact with membrane through electrostatic and h-bonding interactions. Lipid-anchored proteins: associate with membranes through covalently linked lipid anchors. Form ionic interactions, h-bonds with polar head groups of membrane lipids or with integral proteins. Interact with non-polar membrane core by inserting hydrophobic loop or amphipathic alpha-helix. Part of the protein that contacts the non-polar core of the bilayer is dominated by alpha-helices/beta sheets because they neutralize the polar n-h and c=o in the peptide backbone through h-bond formation. Only 10-30% of transmembrane proteins have single transmembrane segment. E. g. glycophorin: most of it is outside the red blood cell, exposed to aqueous milieu, 19 hydrophobic amino acid residues just the right length to span cell membrane if it"s coiled in an alpha helix shape. E. g. monoamine oxidase: each monomer of the protein binds to the membrane through a c-terminal transmembrane alpha helix, residues in 2 loops also provide non-polar residues to participate in membrane binding.
