Proper nomenclature is important for distinguishing plasmids. The “p” in pYES2.1 denotes that it is a plasmid, while the remainder of the plasmid name is a code used by the researchers who constructed the plasmid. Most likely, the “YE” refers to “yeast expression.” In this course, we will follow the convention of denoting the plasmid backbone in normal font, followed by a hyphen and then the name of the cloned ORF in italics. In our experiments:
pYES2.1-MET1 would designate the S. cerevisiae MET1 gene cloned into pYES2.1.
pYES2.1-Met1 would designate the S. pombe Met1 gene cloned into pYES2.1. (Recall from Chapter 6 that S. cerevisiae genes are unusual in using 3 capital letters for their names.)
pYES2.1 -lacZ+ would designate the bacterial LacZ gene cloned into pYES2.1. (Note: bacterial gene names are not capitalized. Plus sign indicates wild type gene.)
The S. pombe ortholog of an S. cerevisiae gene may not share the same gene number. Many of the S. pombe genes received their names due to their homology to previously identified S. cerevisiae genes, but some S. pombe genes had been named before their DNA sequences were known. For example, the ortholog of S. cerevisiae MET2 in S. pombe is Met6.