Answer: The nucleus is separated from the cytoplasm by a phospholipid bilayer known as nuclear envelope. Transport of macromolecules across the nuclear membrane takes place through specialized nuclear pores. Proteins found in the nucleus are synthesized in the cytoplasm and imported into the nucleus through nuclear pore complexes. Such proteins contain a nuclear- localization signal (NLS) that directs their selective transport into the nucleus.4 proteins are required for nuclear localization- importin , importin , NTF-2 & Ran. Answer-A: It has been previously said that nuclear localization signal(NLS) is located within the amino acid sequence of a protein which needs to be localized in the nucleus. Importins actually identify this signal within the protein and interacts with it and facilitates the transfer of nuclear protein from cytosol to nucleus. If the NLS is not present and has already been deleted, the importins won\'t be able to identify the protein and transport them into the nucleus. In this present case, deletion mutation of the protein has been performed to identify the part of the amino acid sequence acting as NLS. In addition leptomycin B has also been added which prevents nuclear export and is not relevant with respect to nuclear localization and NLS. NLS is located in the amino acid range- 240-357. It is so because it can be observed from the available results that localization into the nucleus takes place for deletion mutants having amino acids - 1-576, 115- 576, 240-576 , 240- 357 & 115-357. Conclusions: 115-576 - NLS is not located in amino acid sequence 1-115 240-576 - NLS is not located within the amino acid sequence - 1-239 240-357 - NLS is not located in amino acid sequence 1-240 & 358-576 115-357 - NLS is not located within 1-115 & 358-576 Localization takes place in all the above cases and the deletion mutants are always found in the nucleus and they may or may not be found in the cytoplasm. From assessment of these conclusions, it can only be inferred that NLS is located in the range 240-357. Answer B: There are some “shuttling” proteins that contain a nuclear-export signal (NES) that stimulates their export from the nucleus to the cytoplasm through nuclear pores, in addition to an NLS that results in their reuptake into the nucleus. Export of proteins from the nucleus is mediated by proteins known as Exportins which first forms a complex with Ran·GTP and then binds the NES in a cargo protein. Once it crosses the nuclear pore, the Ran GAP associated with the NPC cytoplasmic filaments stimulates conversion of Ran·GTP to Ran·GDP. The accompanying conformational change in Ran leads to dissociation of the complex. The NES-containing cargo protein is released into the cytosol, while exportin 1 and Ran·GDP are transported back into the nucleus through NPCs. In this case, NES is located in the amino acid region 115-240. It is speculated to be so because: The deletion mutant bearing amino acids 115-576 possess the NES since i.

1. Answer:
The nucleus is separated from the cytoplasm by a phospholipid bilayer known as nuclear
envelope. Transport of macromolecules across the nuclear membrane takes place through
specialized nuclear pores. Proteins found in the nucleus are synthesized in the cytoplasm and
imported into the nucleus through nuclear pore complexes. Such proteins contain a nuclear-
localization signal (NLS) that directs their selective transport into the nucleus.4 proteins are
required for nuclear localization- importin , importin , NTF-2 & Ran.
Answer-A:
It has been previously said that nuclear localization signal(NLS) is located within the amino acid
sequence of a protein which needs to be localized in the nucleus. Importins actually identify this
signal within the protein and interacts with it and facilitates the transfer of nuclear protein from
cytosol to nucleus. If the NLS is not present and has already been deleted, the importins won't
be able to identify the protein and transport them into the nucleus. In this present case, deletion
mutation of the protein has been performed to identify the part of the amino acid sequence acting
as NLS. In addition leptomycin B has also been added which prevents nuclear export and is not
relevant with respect to nuclear localization and NLS.
NLS is located in the amino acid range- 240-357. It is so because it can be observed from the
available results that localization into the nucleus takes place for deletion mutants having amino
acids - 1-576, 115- 576, 240-576 , 240- 357 & 115-357.
Conclusions:
115-576 - NLS is not located in amino acid sequence 1-115
240-576 - NLS is not located within the amino acid sequence - 1-239
240-357 - NLS is not located in amino acid sequence 1-240 & 358-576
115-357 - NLS is not located within 1-115 & 358-576
Localization takes place in all the above cases and the deletion mutants are always found in the
nucleus and they may or may not be found in the cytoplasm. From assessment of these
conclusions, it can only be inferred that NLS is located in the range 240-357.
Answer B:
There are some “shuttling” proteins that contain a nuclear-export signal (NES) that stimulates
their export from the nucleus to the cytoplasm through nuclear pores, in addition to an NLS that
results in their reuptake into the nucleus. Export of proteins from the nucleus is mediated by
proteins known as Exportins which first forms a complex with Ran·GTP and then binds the NES
in a cargo protein. Once it crosses the nuclear pore, the Ran GAP associated with the NPC
cytoplasmic filaments stimulates conversion of Ran·GTP to Ran·GDP. The accompanying
conformational change in Ran leads to dissociation of the complex. The NES-containing cargo

2. protein is released into the cytosol, while exportin 1 and Ran·GDP are transported back into the
nucleus through NPCs.
In this case, NES is located in the amino acid region 115-240. It is speculated to be so because:
The deletion mutant bearing amino acids 115-576 possess the NES since it is observed to be
localized in the cytoplasm whereas the deletion mutant bearing 240-576 amino acids was not
observed to be localized in cytoplasm. From this it follows that the NES is located in the amino
acid range 115-240. The conclusion is further substantiated by the deletion mutant bearing amino
acids 240-357 & 115-357. While the former was not found to be localized in cytoplasm under
the influence of NES the latter bearing additional amino acids 115-239 was observed to be
localized in the cytoplasm.
Solution
Answer:
The nucleus is separated from the cytoplasm by a phospholipid bilayer known as nuclear
envelope. Transport of macromolecules across the nuclear membrane takes place through
specialized nuclear pores. Proteins found in the nucleus are synthesized in the cytoplasm and
imported into the nucleus through nuclear pore complexes. Such proteins contain a nuclear-
localization signal (NLS) that directs their selective transport into the nucleus.4 proteins are
required for nuclear localization- importin , importin , NTF-2 & Ran.
Answer-A:
It has been previously said that nuclear localization signal(NLS) is located within the amino acid
sequence of a protein which needs to be localized in the nucleus. Importins actually identify this
signal within the protein and interacts with it and facilitates the transfer of nuclear protein from
cytosol to nucleus. If the NLS is not present and has already been deleted, the importins won't
be able to identify the protein and transport them into the nucleus. In this present case, deletion
mutation of the protein has been performed to identify the part of the amino acid sequence acting
as NLS. In addition leptomycin B has also been added which prevents nuclear export and is not
relevant with respect to nuclear localization and NLS.
NLS is located in the amino acid range- 240-357. It is so because it can be observed from the
available results that localization into the nucleus takes place for deletion mutants having amino
acids - 1-576, 115- 576, 240-576 , 240- 357 & 115-357.
Conclusions:
115-576 - NLS is not located in amino acid sequence 1-115
240-576 - NLS is not located within the amino acid sequence - 1-239
240-357 - NLS is not located in amino acid sequence 1-240 & 358-576

3. 115-357 - NLS is not located within 1-115 & 358-576
Localization takes place in all the above cases and the deletion mutants are always found in the
nucleus and they may or may not be found in the cytoplasm. From assessment of these
conclusions, it can only be inferred that NLS is located in the range 240-357.
Answer B:
There are some “shuttling” proteins that contain a nuclear-export signal (NES) that stimulates
their export from the nucleus to the cytoplasm through nuclear pores, in addition to an NLS that
results in their reuptake into the nucleus. Export of proteins from the nucleus is mediated by
proteins known as Exportins which first forms a complex with Ran·GTP and then binds the NES
in a cargo protein. Once it crosses the nuclear pore, the Ran GAP associated with the NPC
cytoplasmic filaments stimulates conversion of Ran·GTP to Ran·GDP. The accompanying
conformational change in Ran leads to dissociation of the complex. The NES-containing cargo
protein is released into the cytosol, while exportin 1 and Ran·GDP are transported back into the
nucleus through NPCs.
In this case, NES is located in the amino acid region 115-240. It is speculated to be so because:
The deletion mutant bearing amino acids 115-576 possess the NES since it is observed to be
localized in the cytoplasm whereas the deletion mutant bearing 240-576 amino acids was not
observed to be localized in cytoplasm. From this it follows that the NES is located in the amino
acid range 115-240. The conclusion is further substantiated by the deletion mutant bearing amino
acids 240-357 & 115-357. While the former was not found to be localized in cytoplasm under
the influence of NES the latter bearing additional amino acids 115-239 was observed to be
localized in the cytoplasm.