Annotating proteins

Let’s next discuss proteins in more detail. Each protein has regions or domains that can be annotated and give us further insight into the biological function of that portion of the protein. With this information, we can further reason about the potential impact of variants in that domain. For now, we’ll focus on 2D protein structure, meaning we look at the primary amino acid sequence without trying to fold or understand the 3D structure of the protein. We’ll talk more about structural prediction in Chapter 9, Protein Structure and Proteomics.Much like the structure of a gene, proteins have various regions that perform different functions. Let’s take a look at the 2D structure of a typical protein:

Figure 6.13 – Protein structure overview

Proteins in 2D are read from left to right, and the left side is called the N-terminus. Just like DNA, amino acids have a directionality, with an NH₂ group at the beginning and COOH or carboxyl...