Anyway, this post is inspired by the Biochemistry course I'm taking this semester. It could, however, be a sort of continuation to my last post. Then, I mentioned DNA and RNA, but now leaving the realm of nucleotides, we move on to proteins. Proteins are an incredibly diverse set of molecules, taking on such 3D shapes and performing such amazing functions, and in some cases at such extraordinarily high speeds and even achieving 100% efficiency, that its a joy to know that its all happening inside of you.
Proteins are a translation of the genetic code. They are the means by which the information stored in the genetic material is utilized. At this point, I cannot stop myself from repeating how awesome RNA is by mentioning tRNA molecules. Even though they work in sync with many different proteins, tRNA molecules are the only molecules that can 'read' the genetic code and know what its saying.
Even though there are many cool proteins about - almost all of them essential since they help us survive - let me try to explain something about two protein families that got me especially interested:
1) Infectious proteins? Not quite, but close. So we generally know bacteria and viruses to wreak havoc and spread infectious diseases. However, one of the greatest surprises of modern medicine is that certain infectious neurological disease can be transmitted by proteins (I don't know if that comes as a shock to people, certainly surprised me). Back in the 90's, these proteins had their bit of fun in England and caused an outbreak of Mad Cow Disease or formally bovine spongiform encephalopathy. The proteins causing such diseases are called prions and what makes it slightly ironic is that they are derived from a 'normal' protein called PrP. What happens is that something goes wrong with the folding of the PrP and these misfolded proteins clump together. These clumps then become nuclei of evil activity and attract normal proteins towards themselves forming larger aggregates that disrupt normal function. Now, the transfer of these protein aggregates can cause the disease to become infectious.
The interesting thing about PrP is that its usually found in the brain and prions are associated with long-term memory. So, as it turns out, these pestering proteins are also the cause of (though non-infectious) some neurodegenerative diseases such as Alzheimer's and Parkinson's, having toxic effects on neurones and causing loss of memory and motor control.
2) As if I didn't think cancer was already too intelligent for our good, I discovered this new devilry on the part of tumor cells. These cells not only have the nerve to become resistant to drugs that were originally quite toxic to them, but resistance to one drug gives them the ability to become less sensitive to other drugs also. This is known as multidrug resistance. Tumor cells have this ability because of the expression of a protein, aptly named multidrug-resistance (MDR) protein. So, when these cells are exposed to a drug, the MDR pumps the drug out of the cell before the drug can exert its effects, which is extremely clever of the protein even though its such a traitor.
Proteins can be so cruel.