Overexpression of human virus surface glycoprotein precursors induces cytosolic unfolded protein response in Saccharomyces cerevisiae

Table 1 Identification of yeast proteins involved in recombinant MuHN and MeH expression.

Spot No.	Name^a	Fold Change^b	ID Method^c	Function, Process^d	Localization	Fraction overexpressed^e
1,2 3	Ssa1/2 Ssa4	2.4 ± 0.2^f	M, ESI ESI	Chaperone, Stress response Chaperone, Stress response	Cytoplasm, cell wall Cytoplasm, nucleus	All fractions except insoluble under denaturing conditions All fractions except insoluble under denaturing conditions
4	Kar2	3.8 ± 0.4	M	Chaperone, UPR	Endoplasmic reticulum	Soluble at high salt concentration
5	Sse1	2.3 ± 0.2	ESI	Co-chaperone, Stress response	Cytoplasm	Soluble at high salt concentration
6	Hsc82	2.1 ± 0.3	M, ESI	Chaperone, Stress response	Cytoplasm, mitochondrion	Soluble at high salt concentration
7	Eno2	1.5 ± 0.2	M	Lyase, Glycolysis	Cytoplasm, vacuole	Totally soluble
8	Sgt2	1.6 ± 0.2	ESI	Co-chaperone, Response to heat	Cytoplasm	Soluble in non-ionic detergent
9	Sti1	1.6 ± 0.3	M	Co-chaperone, Stress response	Cytoplasm	Soluble at high salt concentration
10	Hsp104	2.6 ± 0.3	ESI	Chaperone, Stress response	Cytoplasm, nucleus	Soluble at high salt concentration
11	Hsp26	0.7 ± 0.1	M	Chaperone, Stress response	Cytoplasm, nucleus	Insoluble under native conditions
12	Hsp42	ND^g	M	Chaperone, Stress response	Cytoplasm, cytoskeleton	Insoluble under native conditions
13	Bgl2	ND^g	M	Glycosidase, cell wall organization	Cell wall	Insoluble under native conditions
14	Pep4	ND^g	M	Protease, respon- se to starvation	Vacuole, mitochondrion	Insoluble under native conditions
15	Tef2	NA^g	ESI	Elongation factor, Translation	Cytoskeleton, Ribosome	Insoluble under denaturing conditions

^aAccepted name from the Saccharomyces genome database (SGD) and YPD. Spots 1 and 2 represent mixtures of similar proteins Ssa1 and Ssa2 (97% identity) at an unknown ratio.
^bFold change represents ratio between the relative protein amounts (%Vol) in whole cell lysates of the MuHN/MeH expressing and control cells, respectively, ±SD.
^cProtein identification method abbreviations: M, MALDI-fingerprint; ESI, nLC-ESI-MS/MS analysis.
^dMolecular function, biological process and localization are noted according to UniProtKB and SGD.
^eLysates were fractionated into different fractions based on protein solubility under various conditions as described in Methods and shown in Figure 3. Fractions with the strongest overexpression of identified yeast proteins in MuHN and/or MeH variants compared to control samples are indicated.
^fThree closely packed spots 1, 2 and 3 were merged and the fold change calculated for one common Ssa spot.
^gND - not determined; NA - not assayed.

ISSN: 1475-2859