INVSc1 Chemically Competent Cell

For the first use of Carrier DNA，boil the tube containing Carrier DNA in boiling water for 5 min，then place it on ice immediately and store at -20℃ after use for later standby. Thaw Carrier DNA on ice before each use，and re-denature it after 3-5 repeated freeze-thaw cycles. Competent cells should be thawed on ice. High concentration of plasmid for transformation can appropriately reduce the bacterial dosage for plate coating. Saccharomyces cerevisiae is temperature-sensitive with an optimal growth temperature of 28℃-30℃，and temperatures over 31℃ will inhibit its growth. Yeast grows slower in dropout medium than in YPDA medium; the more nutrient-deficient components the medium has，the slower the yeast grows. INVSc1 is a diploid strain of Saccharomyces cerevisiae，specially designed for eukaryotic recombinant protein expression and serves as the standard host matched with the pYES series vectors. The pYES2 plasmid is used in combination with INVSc1 yeast，which can activate the transcription of the GAL1 promoter on pYES2 and further initiate the expression of downstream recombinant proteins. As a zygote strain，INVSc1 can be directly transformed with pYES2 plasmid via the PEG/LiAc method. The pYES2 plasmid carries the URA selection marker and can be screened on SD-URA plates. The transformation efficiency of INVSc1 competent cells tested with pYES2 plasmid (5857bp，Amp?) is higher than 10? cfu/μg DNA. Genotype: MATa his3Δ1 leu2 trp1-289 ura3-52/MATα his3Δ1 leu2 trp1-289 ura3-52