1. Isolate short cDNA fragments
    (tags) that are unique for each
    individual mRNA species

2. Ligate tags to form large DNA
    molecules (concatemers)

3. Determine extent of tag
    expression by checking the
    frequency with which each
    individual tag is represented
    in  the sequences of the
    concatemers

A digital expression profile is provided
which offers all the advantages of SAGE^TM

• The bias inherent in PCR-based amplification processes is avoided by SAGE^TM.

• The serial quantification of short mRNA-specific DNA fragments out-numbers the data obtained from EST sequencing by a factor of up to 40. The high efficiency inherent in the method provides reliable and sensitive digital expression profiles.

• SAGE^TM not only describes the transcriptome of any given cell most comprehensively, but also quantifies each mRNA species within the expression profile.

• The digital nature of the data generated by SAGE^TM allows multiplex comparisons with other tissues without any additional wet laboratory work, thus saving time and money!

• SAGE^TM leads to the discovery of unknown genes. Experimental data from a study¹⁾ of approximately 300,000 transcripts in normal and cancer tissue indicate that 86% of all transcripts were expressed at less than five copies per cell. About 49% of these low abundant transcripts discovered by SAGE^TM did not match any entry in public databases.

1) Zhang, L. et al. (1997) Science 276, 1268-1272

• SAGE^TM is an excellent approach to obtain an exact gene expression profile wherever it is required.

• SAGE^TM leads to the discovery of unknown genes. It helps answer all questions where the knowledge of exact gene expression profile is the key to success.

• The analysis of the gene expression in diseased and healthy tissue by SAGE^TM unveils new potential drug targets in a wide variety of afflictions such as atherosclerosis, diabetes, cancer, inflammation or stroke.

• SAGE^TM helps speed up drug development program by unambiguously defining the regulated expression of individual genes under the influence of the lead compound.

• Reliable and new diagnostic markers are detected by generating gene expression profiles at different stages of the diseases.

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