Hello Rohit Mantena

Cells import extracellular macromolecules by receptor-mediated endocytosis.

Clathrin-coated pits and vesicles provide an efficient pathway for taking up specific macromolecules from the extracellular fluid. In this process, the macromolecules bind to complementary transmembrane receptor proteins, accumulate in coated pits, and then enter the cell as receptor-macromolecule complexes in clathrin-coated vesicles. Receptor-mediated endocytosis provides a selective concentrating mechanism that increases the efficiency of internalization of particular ligands more than a hundredfold, so that even minor components of the extracellular fluid can be specifically taken up in large amounts without taking in a correspondingly large volume of extracellular fluid. Moreover, cells are also continually ingesting fluid and solutes by pinocytosis and large particles are most efficiently ingested via large vesicles called phagosomes by a process called phagocytosis.

So, there are many factors involved including the size and charge of the protein molecule which need to be taken into consideration when you add the transcription factor (specifically ATF4) directly to cell culture.

You may refer to the research article below for methods of protein delivery into cells.

https://portlandpress.com/biochemsoctrans/article-abstract/48/2/357/222602/Methods-for-protein-delivery-into-cells-from?redirectedFrom=fulltext

I hope this helps.

Best,

The short answer is no, proteins added to the media of cultured cells are unlikely to cross the cell membrane without some type of carrier. But, you can transfect cells with another plasmid if you make stable cells and use another selectable marker, such as puromycin or neomycin, or you can do transient transfection with two plasmids at one time.

Hello Rohit Mantena May be you can use this reagent for transfection of proteins http://www.genlantis.com/bioporter-reagent.html which has been tested and cited for SY5Y cells.

Best

Surya