Question

You are investing the function of gene X in human cells. You have two different cell types in culture. One is the hepatic cells isolated from an individual. The other is the hematopoietic stem cells isolated from the same individual. Upon quantitative reverse transcriptase (RT)-PCR and Western blot analysis, you discovered that hepatic cells express higher level of gene X than hematopoietic stem cells do. Another difference you noticed were that protein X (produced from gene X) from hematopoietic stem cells is 54 kDa in size but it is 68 kDa from hepatic cells. Explain what are potential biological processes that contributed on the differential gene expression levels and different sizes of the same gene.

Answer 1

Ans:- The difference between the expression level of protein X in hepatic cells and Heamatopieotic stem cells will be due to the fact that their might be high level of signal or transcrption factor present in hepatic cells that regulate the high level of expression. On the other hands Heamatopieotic stem cells lack the strong signal or lack the active Transcription factor inside cell that leads to lower expression level of protein X in hematopoietic stem cell in contrast to hepatic cells. Another, reason might be hepatic cells activator or receptor received the signal from time to time to maintain the level of gene X in these cells whereas hematopoietic stem cells does not

The size of the protein X varies from 54 kDa in hematopoietic stem cells to 68 kDa in hepatic cells due to the exon skipping. Exon skipping is a common phenomenon that produces different isoform of same gene. So, it might happen that protein X present in hematopoietic stem cells may have gone exon skipping that leads to production of smaller size protein X. In contrast, hepatic cell have produced full length of protein X that's why it's size is 68 kDa.

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