What is the importance of different isoforms with same CDS regions and same proteins? Why in nature it is needed?

Question

[afashmalik]

I was comparing isoforms of a gene and got realised that they all were having the same CDS region though their 5' UTR regions were different but their 3' UTR regions were same. Can someone explain what is the purpose and importance of these isoforms when they have the same CDS and same proteins and also what is the purpose of having different 5'UTRs but same 3' UTR regions (even on transcript does not have 3' UTR). Thank you!

[Denise CS]

Although the CDS is the same and therefore the translation, different UTRs may contain some elements (CpG islands, Transcription Start Sites) that can have a different impact depend on the time and mode of transcription. Or different polyadenylation sites and signal. Have you got concrete examples? It may help to visualise them in the context of the gene and its other transcripts.

[afashmalik]

Actually the gene I am working on has the same condition where the all the isoforms of the gene codes for the same enzyme and how this may help to visualise them in the context of the gene and its other transcripts? I could not understand your this point. Can you explain this how?

[Denise CS]

Sorry if my point was confusing. I just wanted to see an example of such transcripts in a nice visualisation tool such as Ensemblenter link description here. Look at ICAM2-010 and ICAM2-012. Their 5'ends are different although the protein starts at the same ATG, it's in the same frame (note that both are partial translation though as it stands). How many isoforms have you got for your gene? Are the available in the public domain? What are they called?

[keith.hughitt]

Check out, for example, Wikipedia - 5'UTR role in translational regulation and Barrett et al, 2012.

Answer 1

[WouterDeCoster]

Probably a regulatory difference, tissue-dependent transcription.

Answer 2

[afashmalik]

Actually the gene I am working on has the same condition where the all the isoforms of the gene codes for the same enzyme and how this may help to visualise them in the context of the gene and its other transcripts? I could not understand your this point. Can you explain this how?

[Emily]

But the protein may be required in a number of different circumstances. The different 5' UTRs will mean there are different promoter regions, allowing the protein to be expressed in response to different combinations of transcription factors.

[afashmalik]

But promoter regions are not present in 5' UTR region or you mean something else?

[Emily]

No, they're upstream. But different 5' UTRs mean they have different transcription start sites and different promoters.