DAD1 is both an enzyme, and the username of one of my followers and (I hope) biggest fans. This post was requested by him, because being the power geek and brilliant father that he is, when he needed a username to follow my blog, he went online and promptly found himself an enzyme named Dad. And now, of course, he wants to know what his enzyme does. So this is for you, DAD1.
DAD1’s full title is Defender Against Cell Death 1 (already I sense that my Dad is really excited, his enzyme has a genuinely cool name). Not a huge amount is actually known about it, but as its name suggests, it does appear to have a role in stopping the process of cell death, which is known as apoptosis.
DAD1 is not in fact a functional enzyme in itself; instead it works as a subunit of another enzyme, N-oligosaccharyl transferase, whose job is to hang around popping sugars onto certain proteins, a process known as glycosylation. Glycosylation is essential in our cells for a number of reasons; some proteins for example cannot fold into the correct shape without the right sugars attached in the right places, and incorrect or incomplete folding means they cannot function properly. Other proteins may be unstable and prone to degradation if they are not glycosylated in precisely the right way, and if they degrade then they cannot do their job, obviously.
So, knowing that DAD1 stops cell death from occurring, we can assume that the correct glycosylation of certain proteins is important in somehow suppressing a pathway that would initiate programmed cell death. When there is no DAD1 being produced, the pathway is no longer suppressed and the cell can then effectively kill itself. Most of the time, cells don’t want to kill themselves, so they will be busily producing DAD1 and other enzymes with similar roles; however, if a circumstance arises in which the cell needs to die, the cell will stop making DAD1 so that it can begin apoptosis.
An example of such a circumstance is during the development of hands and feet in the womb; at first they are a reasonably shapeless mass of cells and then, as the bones begin to develop, the cells between the fingers and toes die, separating the digits. This, obviously, is a Good Thing, otherwise we’d be fairly useless creatures.
Apoptosis usually is a good thing actually; it is the cell dying because it needs to, not because it is killed by an external force (that would be necrosis). But, of course, apoptosis is only any use if it is controlled and regulated extremely carefully, and this is why we need such molecular superheroes as DAD1. What a legend.