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Discover StorPro organelles
Mechanism of action

StorPro® organelles are packaged as 1 to 3 micrometer intracellular compartments surrounded by a membrane derived from the endoplasmic reticulum (ER). These structures are formed by self-assembly of recombinant Zera® domains derived from a natural storage protein found in cereal seeds. The sequence of this peptide incorporates conserved molecular signals which are recognizable by any ER.  This recognition catalyzes formation of de novo storage organelles which sequester and accumulate the Zera® peptide and its fusion partners in complex with appropriate ER-associated molecular chaperones. Even when produced in mammalian cells, these non-secretory vesicles are sufficiently dense for simple mechanical isolation.

  1. RNA traduction (fusion of Zera® peptide and product)
  2. Internalization via signal peptide
  3. Zera® peptides interact with the ER membrane, self-assemble, associate with chaperones, and induce the formation of de novo storage organelles
  4. The fusion of Zera®-peptide and protein of interest are sequestered inside the StorPro® organelles and are insulated from proteolytic degradation
    Formation of Zera induced storage organelles

    cho pattern

     

    Accumulation of target protein in transfected mammalian cells

    A: Without the Zera® assembler peptide recombinant proteins are distributed diffusely throughout the cell.

    B: Fluorescent proteins fused to Zera® peptides are localized to StorPro® organelles, discrete storage structures containing large quantities of protein in a soluble, functional form.

    The unique density of the StorPro® organelles facilitates easy recovery by a simple gradient process: the starting biomass is mechanically homogenized, then centrifuged, and the intact product-containing organelles are recovered as a characteristic fraction. Most of the non-product biomass and cellular debris is eliminated by this rapid and low-cost procedure which can be followed by additional downstream wash steps, cleavage, and final affinity or chromatographic purification.


    Upstream Yield Enhancement
    Subcellular isolation of recombinant proteins in StorPro® organelles has the two-fold advantage of a) preventing biological activity of the product from perturbing cell metabolism, while b) insulating the product from deleterious proteolytic and protein-modifying activities.  
    The combined result is increased expression levels and a more uniform, higher quality product. 


    Recovery of the designed storage organelles
    		 
    The easy isolation of StorPro® organelles makes them an extraordinary enrichment tool. After washing, the StorPro® organelles shown in the pellet fraction on the adjacent figure contain up to 50% epidermal growth factor (EGF). 

    Downstream Efficiency
    The Zera® technology also facilitates product enrichment in the early stages of recovery following cell culture. The high density of the StorPro® organelles allows their recovery by physical fractionation techniques, one step replacing the three typical primary recovery steps (clarification, concentration and product capture). This approach is particularly well-suited to proteins which are not amenable to secretion and which are thus otherwise difficult to manufacture in typical high-efficiency cell based systems.
    Purification of Zera proteins
    The last steps of purification include solubilization of the StorPro® organelle membrane, fusion cleavage and final polishing.

    These conventional steps are performed on material remarkably more concentrated than in traditional protein production processes.
    When appropriate, the downstream process can be adapted to yield various product embodiments ranging from intact StorPro® organelles or purified fusions (of potential interest for enhancing oral or dermal delivery, vaccine formulation adjuventicity or protein presentation) to fully cleaved and highly homogeneous products.