Biology 2382B Lecture Notes - Lecture 20: Uniporter, Semipermeable Membrane, Cytosol
24 Aug 2013
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Document Summary
Type iv proteins have multiple transmembrane domains and the orientation of each hydrophobic helix of the transmembrane domains depends on the positively-charged residues next to the topogenic sequence. Type iv proteins tend to have alternating sa signal sequences and sta signal sequences, often totalling in 7 transmembrane domains. In type i proteins, the n-terminal signal sequences are always luminal and the sta signal sequence makes up the transmembrane domain. In type iv proteins, a repeating arrangement of sa and sta signal sequences are present. ), and active transport (atp pumps, antiporters, symporters, etc. Passive diffusion is a form of membrane transport that does not require any membrane proteins. It is for molecules that can freely cross the membrane (e. g. oxygen). Molecules need to be relatively aqueous, but also slightly-soluble in lipids in order to cross the plasma membrane (e. g. ethanol dissolves in water, but has lipophilic characteristics).
