MIT Department of Biology 7.013: Introductory Biology - Spring 2005 Instructors: Professor Hazel Sive, Professor Tyler Jacks, Dr. Claudette Gardel 7.013 SECTION PROBLEM PROTEIN SECRETION AND LOCALIZATION The following 4 proteins are found in a yeast cell. Protein 1 is a cytoplasmic protein Protein 2 is a secreted protein Protein 3 is a secreted protein Protein 4 is a plasma membrane protein Describe how each of the following mutations (a-f) affect the localization of these above proteins. outside the cell in the golgi in the cytoplasm in the ER in transport vesicles in the plasma membrane in secretory vesicles in the nucleusFill in the blanks below with the term(s) from the previous list to indicate the resulting locations of the proteins. a) Mutation A is a deletion of the signal sequence protein 2. Where would the majority of the following proteins be found in a strain with this mutation? Protein 1? Protein 2? Protein 3? Protein 4? b) Mutation B inactivates the SRP (signal recognition particle), preventing it from binding to signal sequences. Where would the majority of the proteins be in a strain with this mutation? Protein 1? Protein 2? Protein 3? Protein 4? c) Mutation C results in a deletion of the transmembrane domain of protein 4. Where would the majority of the following proteins be found in a strain with this mutation? Protein 1? Protein 2? Protein 3? Protein 4? d) Mutation D blocks the fusion of the transport protein vesicles with the Golgi membrane. Where would the majority of the following proteins be found in a strain with this mutation? Protein 1? Protein 2? Protein 3? Protein 4? e) Mutation E eliminates the SRP docking protein on the ER membrane. Where would the majority of the following proteins be found in a strain with this mutation? Protein 1? Protein 2? Protein 3? Protein 4? f) Mutation F inserts a signal sequence in frame at the beginning of Protein 1. Where would the majority of the following proteins be found in a strain with this mutation? Protein 1? Protein 2? Protein 3? Protein
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