Final answer:
The protein responsible for resolving Holiday junctions in yeast is Mus81. It forms an endonuclease complex with Mms4, which is essential for meiotic recombination and DNA repair. Mus81 differs from Rad50, Dmc1, and Rad51, which have different roles in DNA repair and recombination.
Step-by-step explanation:
In yeast, the protein that is a component of an endonuclease which resolves Holiday junctions is Mus81. The Mus81 protein forms a complex with another protein known as Mms4 (in yeast) or Eme1 (in other eukaryotes) to comprise the Mus81-Mms4/Eme1 endonuclease. This complex is critical for the resolution of Holiday junctions, which are intermediates in the recombination process that occurs during meiosis and in some DNA repair pathways.
Holiday junctions are a crucial aspect of genetic recombination, where they allow for the exchange of genetic material between homologous chromosomes. The Mus81-Mms4/Eme1 endonuclease complex cleaves these junctions, ensuring proper segregation of chromosomes during cell division. Failure to resolve Holiday junctions can lead to chromosome missegregation and genetic instability. The other proteins listed, such as Rad50, Dmc1, and Rad51, also play significant roles in DNA repair and recombination but are not directly responsible for cleaving Holiday junctions. For example, Rad51 and Dmc1 facilitate strand invasion and homology searching during homologous recombination, while Rad50 is part of the MRN complex involved in double-strand break repair.