I have read a paper where this notation for protein names is used:

Myod+ and Myod-

(or another example, Myog+, Myog-).

What does this indicate? In the paper I'm reading, and some brief googling, it seems that Myog is itself a protein, and not that there are two kinds called Myog+ and Myog-.

Examples are here (the one I'm reading) (Figure 6c), or here (page 3, pdf page (journal page 958)).

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    $\begingroup$ The paper you linked is not open-access, so many people won't be able to help you. However, as a common convention, ProtX+ and ProtX- typically refer to cells, tissues, or individuals that either express or don't express a particular Protein X. $\endgroup$ – MattDMo Sep 18 '20 at 1:53
  • $\begingroup$ Oh okay, that makes sense. Thank you. Sorry I didn't realize it wasn't open source. It looks like the second one is available though (if I open in incognito, I can access) $\endgroup$ – Chris Sep 18 '20 at 4:35
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    $\begingroup$ To expand on @MattDMo , italicized names indicate genes, with the + or – being used to describe either genome or cell with or without an active copy of the gene and thus able to make the protein, the name of which may or may not be the unitalicized form of the gene. (Many genes are named for the phenotype they convey or some other reason when they are discovered before the protein product has been identified.) $\endgroup$ – David Sep 18 '20 at 11:26
  • $\begingroup$ @David or....... $\endgroup$ – Bryan Krause Sep 18 '20 at 15:37
  • $\begingroup$ @MattDMo either of those could make a concise answer. Probably not a lot of reference needed for an answer like this; one example might be nice but not really necessary. $\endgroup$ – Bryan Krause Sep 18 '20 at 15:37

The Stem Cell Reports paper linked in the question is open-access, so anyone can download it freely. Unfortunately the Nature paper is not.

There are two different abbreviation conventions being used in the open paper – MyoD+/MyoD- and MyoD+/MyoD-. The italicized version indicates the genotype of the cell, tissue, or individual being referenced, so for example MyoD- indicates the MyoD knockout they made. This convention is very widely used to refer to genes or mRNA.

Examples where the gene name is not italicized refer to the protein product of that particular gene and its presence or absence. So, MyoD+ cells express the wild-type protein, while MyoD- cells do not. This convention is also very widely used to refer to the presence or absence of the indicated protein.

  • $\begingroup$ Are there rules on the site against me sharing the part of the figure I am talking about (that is not open access)? $\endgroup$ – Chris Sep 18 '20 at 18:54
  • $\begingroup$ @user8243 it may be copyright infringement, but I'm not a lawyer. $\endgroup$ – MattDMo Sep 18 '20 at 18:58
  • $\begingroup$ I think my smaller question doesn't require it. Reading through the methods, it seems all of their cells are from embryo sample, and no genes were explicitly knocked out. Then here, does the minus indicate that no expression was observed? Seems like it follows from your answer, but wanted to check $\endgroup$ – Chris Sep 18 '20 at 19:07
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    $\begingroup$ @user8243 the minus can either be used to describe a KO ("no expression is expected"), or to describe the results of an assay where expression is actually tested, such as immunofluorescence or Western blotting. $\endgroup$ – MattDMo Sep 18 '20 at 23:44

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