mRNA is directed either to free polysomes and cytoskeletal-bound polysomes for synthesis of intracellular proteins or to endoplasmic reticulum (ER)-bound polysomes for synthesis of membrane or secreted proteins.
The efficient redirection of mRNA to the ER (see upper figure) was found to depend on the nature of specific Targeting elements, i.e.
- the coding sequence (CDS) of the signal peptide
- the 5' untranslated region (5'UTR)
- the 3' untranslated region (3'UTR)
The incorporation of selected targeting elements into the mammalian host cell by genetically engineering the expression vector used for transfection ensures efficient navigation of the recombinant protein-encoding mRNA to the ER, such that the encoded protein effectively enters the secretory pathway and the product is secreted with high yield.
Our technology enables both enhanced synthesis/secretion of naturally secreted proteins, and secretion of intracellular proteins (see lower figure)