Overview: In its simplest form, PTSelect™ involves adding an siRNA into the gene of interest (GOI) transcript (or individual siRNAs for each protein component in the case of tri-specific antibodies, for example) that leads to transcription of both the GOI and eventual activation of an siRNA.  Our siRNA(s) are not necessarily targeted against a particular endogenous protein, but are targeted against the UTR portion of our mRNAs.  The actual selection process is then performed by transfecting mRNA(s) with a complementary site to an siRNA from the original plasmid. The active siRNA cleaves the mRNA in cells that are transcribing the GOI thereby reducing translation of the mRNA, while uninhibited translation occurs in cells without the GOI and siRNA.  Since we are transfecting mRNA rather than DNA, the expression of the mRNA is transient in nature.  But, this method temporarily marks cells as either GOI/siRNA producing or not and those cells can subsequently be selected for or against.  The mRNA can express a fluorescent marker for FACS processing or a surface marker for magnetic separation.

Benefits: PTSelect is a paradigm shift in cell line selection whose benefits include:

Higher titers – makes more protein product, not more resistance proteins
Better pools – selection marker is against GOI transcription, not another protein on the same plasmid
Shorter timeframes – 10-14 days to a higher quality pool than resistance genes
Less overall effort – final pools in as little as 20 hours of effort
Individual markers for multiple proteins – use different markers for each protein component of complex molecules and select the correct ratio of transcription of each
Cell line engineering – knock-down endogenous genes to improve production
Quality control – follow pool progress with quick quality tests
Easy adoption – no need to switch cell lines, vectors, media