The Proteome: what it is and why protein structure is so important

It’s pretty simple:

The proteome is all of the proteins that are coded for by your DNA!

However, the process of creating proteins is somewhat complicated and to get to those beautiful, functional, molecules, we actually need to start by talking about the ‘central dogma.’

The central dogma of molecular biology was first theorized by Francis Crick in 1957.

It states that DNA codes for RNA which codes for proteins and once a protein is made, there’s no going back!

You can’t code for RNA, DNA, or other proteins from protein!

Proteins are made through the ‘translation’ of messenger RNA.

This is a process that involves a large protein complex called the ribosome which ‘reads’ the RNA and stitches together protein building blocks (amino acids) to create the final molecule.

But why are proteins so important?!?

Because they’re the molecules in our cells that do all of the work!

They:

1) Form the structural components of our cells

2) As enzymes, they perform the complex chemistry that makes life possible

3) They also do cool things like copy DNA, read RNA to create other proteins or serve as signaling molecules!

Since proteins perform basically all of our important cellular functions, their presence, absence or altered performance is what defines disease.

Presence and absence are pretty straightforward:

If a protein is needed and it’s not there…that’s bad.

If a protein isn’t needed and it's there…that’s also bad.

But altered performance might be something that’s a little tougher to wrap your head around, so let’s talk about how proteins actually work!

Something we mention A LOT in molecular biology is that structure equals function.

The structure of most proteins is highly complex and we define protein structure across 4 levels:

Primary Structure - Sequence of the amino acids that make up the protein.

Secondary Structure - 2-dimensional structure of the protein. This includes the local interactions of amino acids with one another through hydrogen bonds and disulphide bridges. The most common secondary structures are the α-helix and β-sheet.

Tertiary Structure - Overall 3-dimensional structure of a protein that forms once all of the secondary structures fold into their final forms and interact with one another.

Quaternary Structure - Formed through the interactions among multiple proteins to create a functional protein complex. Many proteins work together with friends to do their jobs!

‘Ok, cool story, but what does any of that have to do with the proteome?!’

Because proteomics is the study of how all of the proteins in your cells and tissues interact to perform their cellular functions!

And understanding how those things break, including the impact on protein structure, function or interactions with their friends, is how we can use proteomics to predict and prevent disease!