How do transmembrane proteins get anchored in the membrane?
A hydrophobic sequence may trigger opening of the pore sideways, so protein slides out of pore, laterally, into lipid bilayer. These hydrophobic sequences are called ‘stop-transfer’ sequences and/or ‘anchor’ sequences. 2. Types of Proteins that can result (see handout 7A) a. Soluble protein in lumen. Happens if protein passes all the way through the membrane and SP (on amino end) is removed, as above. b. Integral membrane protein anchored in membrane by SP with no cytoplasmic domain. This happens if SP is on the amino end and is not removed. c. Single Pass transmembrane protein — get one of 2 possibilities: (1). Type 1: Amino end is on lumen side of membrane (on E side); Carboxyl end is in cytoplasm (on P side of membrane) One way this could happen: If SP is on amino end, and SP removed, and there is a hydrophobic sequence (acting as a stop-transfer sequence) in the middle of the peptide. (2). Type 2: Carboxyl end is on lumen side of membrane (on E side); Amino end is in cytoplasm (on
