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Protein isoform – one phrase, many meanings

There appears to be a large variation in meaning when talking about protein isoforms, which can be quite confusing. Depending on context it can mean one or more of the following scenarios:

1) Two (or more) different genes in the same genome encoding proteins that are highly similar (<95%?).

2) One single gene that is differentially spliced, or differentially translated to create two (or more) different proteins.

3) One single protein that is differentially post-translationally modified to create two (or more) different versions of the protein.

4) Different conformations of the same protein, eg PrPc and PrPsc.


2 Responses to “ Protein isoform – one phrase, many meanings ”

  • shahab

    given we’ve got these genes; aaa1 and aaa2, they proteins would be AAA1 and AAA2 that perfectly fit into the context of isoforms. at the same time for the sake of argument, there might be these genes; bbb1 and zzz9 which are totally different but encode similar proteins, say XXX1 & XXX2.
    are these pairs both isoforms to the same level?

  • rnc8

    Quick answer, without knowing how different “totally different” is, bbb1 and zzz9 sound like homologs or paralogs, not isoforms.

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