Growth factors can be sorted into families and super-families based on their sequence similarities. Growth factor super-families contain multiple sub-families, which in turn contain multiple growth factors that are encoded by a distinct gene. The TGFβ superfamily, for example, contains at least 10 subfamilies. One of these subfamilies, the bone morphogenic proteins (BMP’s), is comprised of at least 15 different gene products. As growth factors are ligands for transmembrane receptors, each growth factor superfamily has a corresponding family of related receptors.
Growth factors are often highly conserved between species; the amino acid sequence of Activin A is identical between humans and mice, even after 33 million years of evolution. Growth factors that diverge in their amino acid sequence, may or may not retain their bioactivity across species. The divergence of cellular pathways over millions of years means that proteins with largely homologous amino acid sequences, like mature human and mouse Epidermal Growth Factor (EGF), can’t act across species. In emerging spaces like cultivated meat, where human growth factors are used for bovine, porcine and seafood cell culture, understanding the extent of growth factor functionality and activity across species is vital to optimize the cultivation process.
Recombinant growth factors with altered amino-acid sequences can be classed as ‘species-neutral’ as they are manipulated from the wild-type and demonstrate bioactivity across many species, like Qkine’s FGF2-G3. Amino-acid modifications can also increase the stability and potency of growth factors, meaning less protein is needed and can be used for longer. This is a crucial next step in the scale up of cell culture, offering a way to overcome the massive costs currently restricting commercialization and unlocking the potential of innovative markets like cell and gene therapies, regenerative medicine, cultivated meat and bioartificial devices.
Explore our range of high quality, animal free proteins for your cell culture at Qkine.