Replies to post #9330 on GTC Biotherapeutics (fka GTCB)

[cellzc]

As a molecular biologist, I have to say sth about this. glycosylation is a way cells modify proteins. in higher order organisms, most of proteins are glycosylated in order to function properly. The reason that they need to genetically modified yeast is because yeast is quite different from human cells and they dont glycosylate proteins in the same way as human cells do. But if a protein is expressed in transgenic goat, pig or whatever mammals, it should been glycosylated (or modified) in the same way as it's in human cells. So no yeast can beat this. They use yeast just because it's easier to culture, not because it gives better protein.
The BOTTOM LINE is this "glycosylation in genetically modified yeast" is not as fancy as it sounds. and it can't produce proteins better than a transgenic animal.

[jessellivermore]

Are there proteins yeast can not produce ???

The answer is there are proteins yeast can not produce in high enough yields to compete with GTC's platform. Glycolisation is only half the battle. In antibody dependent (cell mediated) immune reponse ADCC. The antibody has two ends. The active end attaches to the target cell surface antigen...the other end....the glycolised end attracts Natural Killer Cells which then destroy the target cell. The glycolization pattern effects the affinity of the NKCs for the antibody.

Many proteins are hard to express in bacterial, yeast or even mamalian cell culture due to the complex 3-dimensional folding patterns necessary for them to function. This is true of plasma proteins as a class.....and is of course an important target for GTC's platform which has little competition at present

[vinmantoo]

We have known about Glycofi for quite some time and you are far too kind towards them and optimistic about them as if they are ready to complete with GTCB. Don't just believe thier press releases. All they have done is to place the human glycosylation enzymes into yeast. While it is an very impressive accomplishment, as Jesse says, glycolyslation is only a part of the battle. There are a large number of protein chaperones in cells, which bind top and fold proteins in an orderly fashion. Many of these are associated with nascent proteins as they are being translated, which helps ensure that the proteins folds in a proper way so that they are stable and functional.

Glycosylation and chaperones also serve to allow the proteins to be moved along the secretory pathway, and for proper folding and even proteolytic cleavage, as part of the targeting mechanism to the appropriate intracellular compartment. Different glycosylations serve primarily to transit the proteins in a pathway from ER surface, to ER lumen, to inner and outer golgi to secretory vessicles, which could lead to its ultimate secretion into the extracellular media. Failure to properly execute any step could cause you to make a alot of worthless non-functional proteins that could still be properly gycoslyated. The advantage of mammary glands is they are designed as secretory machines.