Emily and Zach are two students working in the lab to improve the stability and activity of the newly discovered transport prote
in BCM1 in eukaryotic cells. While introducing mutations into the protein sequence that were predicted to improve the stability and activity of BCM1 Zach convinced Emily to mutate some of the amino acids in the N-terminal signal peptide region of the protein sequence. Subsequently, they expressed this mutated BCM1 protein in eukaryotic cells and observed very little transport across the membrane via the mutate BCM1 transporter in comparison to the levels of transport that was observed via the unmutated BCM1 transporter. Upon further analysis Emily determined that the reduction in transport across the mutated BCM1 transporter was due to mutations made in the signal peptide region of the BCM1 sequence. Explain to Zach the importance of this signal peptide region and disrupting it would lead to reductions in the BCM1 transporter activity.
A mutation in the N-terminal region may alter protein stability
Explanation:
Transport proteins are proteins capable of transporting substances through biological membranes. These proteins are located within cellular membranes where they form channels that allow the movement of substances between the internal and external sides of the membrane. The N-terminus is the first region in the protein that emerges from the ribosome during its synthesis. This region is usually composed of signal peptides consisting of about 30 amino acids required for protein delivery. Moreover, the N-terminal region is also important because it dictates protein degradation by peptidases. Consequently, mutations in the N-terminal region of transport proteins can alter the properties of these proteins, i.e., either by modifying protein stability or by altering protein signaling.
Gel electrophoresis is a lab technique used to separate distinct samples of mixed DNA, RNA, or proteins on the basis of their size. In gel electrophoresis, the molecules to be move from one another by an electrical field through a gel with small pores in it. DNA molecules are negatively charged so they move towards positive charge wells in the electric field and get separated.
After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus is evidence of a discrete nuclear localization signal somewhere on the nucleoplasmin protein.
