Primer extension - yeast tRNA as a negative control (Oct/02/2005 )

I am using primer extension assays to identify the transcription start site. Does any one know why is yeast tRNA used as a negative control with the labelled primers in the negative control reaction.
thanks

Hi , I have tried to find out the answer for this but still did not come up with an answer. yeast tRNA has been used as a blocking agent in northern blots.
Why is it necessary to use yeast tRNA in a control for Primer extension. I found several papers that say that yeast tRNA can bind to MMLV reverse transcriptase.
also in RNAse protection assay it has been used to report no unspecific protection of the probe.
but still I dont understand wht it is needed as a control.
Please help. Can someome explain properly

I don't really know, but if I had to guess I'd say it's because tRNA won't contain a TSS? it has nucleotides and stuff, but shouldn't give a positive result if you are assaying for TSS's

thanks a lot. this sounds logical.