| Term | Definition |
|---|
| synthesis of almost all proteins occur in the | cytosol |
| What are the three protein sorting pathways | transport through nuclear pores, transport across membrane, and vesicular transport |
| Transport Across Membrane leads to | import into mitochondria and chloroplasts and import into the ER |
| Import into ER is the import of | soluble proteins and transmembrane proteins |
| 3 steps in vesicular transport | vesicle formation, vesicle docking, and vesicle fusion with target membranes |
| Vesicular Transport- Secretary Pathway travels | outward |
| Vesicular Transport- Endocytic pathway travels | inward |
| amino acid sequence of a particular protein determines its what | final destination |
| Sorting Signals | sequence of amino acids that directs a particular protein to a particular destination |
| sorting signals are also called | signal sequence |
| sorting signals are how man amino acids in length | 15-60 amino acids in length |
| there are different signals for different | destinations |
| Where are sorting signals located | at N-term (beginning) or C-term of a protein |
| Sorting signals are often cleaved when | the protein arrives at its final destination |
| Sorting Signals are important for what two things | necessary for proper protein sorting and sufficient for proper protein sorting |
| If you delete a sorting signal then | the protein does not get to its proper destination |
| if you add a sorting signal to a protein normally found in the cytosol then | that protein will be directed to a particular organelle |
| For nuclear import, how are proteins going to enter the nucleus | via nuclear pores |
| nucleus as what type of membrane | double membrane |
| nuclear pore is an elaborate structure made up of | ~100 different proteins |
| fibrils are located on | both sides of pores |
| Nuclear localization signal (NLS) | amino acid sequence found in proteins that are destined for the nucleus |
| What are two types of NLS | positively charged amino acids: Lys and Arg |
| To bind to the NLS, the prospective nuclear protein is bound by a | nuclear import receptor |
| complex is guided to pore by what | fibrils |
| complex binds to pore which causes what to happen | causes the pore to open (dilate) |
| the complex is transported into nucleus and then | the receptor signal returns back to the cytosol to be used again |
| proteins moved into nucleus move in what form | fully folded 3D form (stay in 3D conformation and do not fold) |
| Which 4 proteins must unfold to transport across the membrane from the cytosol | peroxisome, ER, mitochondria, chloroplast |
| For Protein Transport into the mito and chloro: Both mito and chloro have | double membranes |
| most of mito/chloro proteins are encoded by | nuclear genes and are made in the cytosol |
| protein import into mito and chloro: they usually have a sorting signal at | N-terminus |
| In chloroplasts, sorting signal is recognized and bound by a | membrane receptor protein |
| In chloroplasts, the complex is going to diffuse laterally to a | contact site |
| In chloroplasts, a protein is translocated simultaneously across both membranes through a | protein translocation channel |
| After translocation is complete, the sorting signal is removed by what | signal peptidase |
| ER is the entry point for other organelles. What does this mean | once a protein enters the ER, it will not go back into the cytosol. but it may go to the golgi, endosome, etc. |
| What are the two types of proteins imported into the ER | soluble proteins and prospective transmembrane proteins |
| Soluble proteins | completely translocated across the ER membrane |
| What are soluble proteins destined for | ER Lumen, Golgi Lumen, Endosome, Lysosome, Secreted (released at Plasma Membrane) |
| Prospective Transmembrane Proteins | only partially translocated across ER membrane |
| Where are prospective transmembrane proteins destined for | ER Membrane, Golgi, Lysosome, Endosome, and plasma membrane |
| In regards to Import into the ER, how are all imports directed into the ER | ER signal sequence |
| ER Signal Sequence | 8 or more hydrophobic amino acids |
| Import to the ER begins before what is complete | before translation is complete |
| "Import to ER is cotranslational" What does this mean | proteins begin to enter the ER before the polypeptide chain is completely synthesized |
| The ER signal sequence of a new polypeptide chain directs | ribosome/transcript/polypeptide complex to the ER |
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