Question

State for each of the eight types of proteins listed below whether you would expect that protein to have one of the four options, and give a short explanation why:
- a nuclear localization signal (NLS),
- a mitochondrial signal sequence,
- an ER signal sequence, or
- no signal sequence.

Insulin = ?
Adenylyl cyclase = ?
Caspase-9 = ?
Rb protein = ?
Cytochrome c reductase subunit = ?
Lysosomal proton (H⁺) pump = ?
Lamin-A protein = ?
Pyruvate dehydrogenase = ?

Thank you!!! :)

Answer 1

a nuclear localization signal (NLS),
- a mitochondrial signal sequence,
- an ER signal sequence, or
- no signal sequence.

Insulin = This protein will have endoplasmic siganl sequence which will be cleaved later after enetring in the ER and further localization for extracellular release.
Adenylyl cyclase = This protein is embedded in the plasma membrane, hence will have endoplasmic reticulum signal sequence which would help to localize in the plasma membrane.
Caspase-9 = These proteins are located in multiple location within the cell such as nucleus, cytosol and mitochndria. Depending on their localization they will have either nuclear ( for nucleus), mitochondrial ( for mitochndria), or no signal ( for cytosol).
Rb protein = This protein will have nuclear localization signal because it is located in the nucleolus. Some eukaryotes may not have signal because these proteins also present in the cytosol.
Cytochrome c reductase subunit = This protein will have mitochondrial signal sequence because it is located in the mitochondria.
Lysosomal proton (H+) pump = This protein will contain the ER signal sequence because it is located in the lysosome.
Lamin-A protein = These proteins are major architectural protein located in the nucleaus, hence these proteins will have nuclear localization signal.
Pyruvate dehydrogenase = This protein would have mitochndria signal sequence beacuse it is located in the mitochondria.