This conserved fungal family is an essential molecular chaperone in the endoplasmic reticulum. Molecular chaperones transiently interact with unfolded proteins to inhibit their self-aggregation and to support their folding and/or assembly. Rot1 is a general chaperone with some substrate specificity, its substrates being the structurally unrelated Kre5 Kre6 Big1 Atg22, which are type I, type II, and polytopic membrane proteins. The dependencies of each for Rot1 do not share similarities. However, their folding does require BiP, and one of these proteins was simultaneously associated with both Rot1 and BiP. In addition, Rot1 may cooperate with BiP/Kar2 in the folding of Kre6 [1].

1: Saccharomyces cerevisiae Rot1 Is an Essential Molecular Chaperone in the Endoplasmic Reticulum. Takeuchi M, Kimata Y, Kohno K; Mol Biol Cell. 2008; [Epub ahead of print] PMID:18508919