Figure 5

Evaluation of artificial UPR induction. A. Relative expression levels of the ER chaperone KAR2 determined by qPCR. The relative expression levels were calculated from the comparative threshold cycle values using the housekeeping actin gene as a control. B. Growth curve of a Hac1p overexpressing strain and an empty vector strain. Overexpression of Hac1p does not lead to a growth defect. C. Analysis of the culture supernatants after Hac1p induction. Lane 2 and 3 correspond to the empty vector and HAC1(S) transformed cells respectively. Two bands are prominently more abundant in the Hac1p overexpressing strain compared to the empty vector control. Mass spectrometry revealed that these bands correspond with Kar2p and Pdip, two ER HDEL-containing chaperones. D. EM pictures of a Hac1p overexpressing GS115 strain. Overexpression of Hac1p leads to the appearance of intracellular membranous structures (see white squares) with a cubic morphology.