Proteome

Your body is made of tiny parts.

These parts are called proteins. They work in many ways. They help you stay healthy.

A whole set of these parts is called a proteome. Different parts of your body have different sets. One cell might have its own set. A virus has its own set too. Scientists study these sets to learn about health. They can even help find sickness. This helps doctors give the right medicine. Studying these parts is very exciting.

Everything in a living thing is made of many parts.

One set of these parts is called the proteome. The proteome is the whole collection of proteins in a cell or an organism. Scientists who study these sets use a word called proteomics.

Different parts of your body have different proteomes. For example, a single cell has its own set. A virus also has its own viral proteome. Even tiny parts inside a cell, called organelles, have their own sets. One part called a mitochondrion can have more than 3,000 different proteins!

Studying the proteome helps us understand health. It can help doctors find cancer. Scientists look for changes in proteins to see if someone is sick.

This helps doctors pick the best medicine for each person.

Scientists use special tools to study these parts. They use a machine called a mass spectrometer. This tool helps identify proteins. They also use a method called electrophoresis. This way, they can separate proteins to see them clearly.

A proteome is the complete set of proteins found in a cell, a tissue, or a whole living thing.

While a genome is the set of instructions, the proteome is the set of proteins actually being used at a specific time. Because different cells do different jobs, they each have their own unique proteome. For example, a tiny part of a cell called a mitochondrion can have more than 3,000 different proteins. Even viruses have their own viral proteome. Scientists who study these sets of proteins use a field called proteomics.

Studying the proteome works by looking at how proteins change under different conditions. Scientists can use special tools to see which proteins are present and how much of them there is. One way is called two-dimensional gel electrophoresis. This method separates proteins by their electrical charge and then by their weight.

Another important tool is mass spectrometry. This machine helps identify proteins by breaking them into small pieces and measuring them.

These steps allow researchers to map out the many different parts of a living system.

Humans first began defining this concept in the 1990s. A scientist named Marc Wilkins coined the term "proteome" in 1994. He shared this idea at a meeting in Siena, Italy. The term was officially published in 1995 in his PhD thesis. Since then, many large projects have tried to map the human proteome. For instance, the Human Proteome Project has published a blueprint that covers more than 90% of predicted protein genes. These projects help us understand the massive variety of proteins in our bodies.

There are many important facts about how large a proteome can be. In bacteria, a proteome might have between 500 and 10,000 different proteins. Viruses are much smaller, often having only about 3 to 1,000 proteins. Human cells are much more complex because of a process called alternative splicing. This means one gene can make many different proteins. Because of this, some estimates say the human body could have over 92,000 proteins. This makes the human proteome much harder to map than a genome.

Understanding the proteome is very helpful for medicine. Doctors use proteomics to find signs of cancer in a patient.

By looking at protein patterns, they can see if a cancer might spread. This helps them create personalized medicine. This means they can pick a specific mix of drugs just for one person. Studying proteins also helps us understand how bacteria grow or how they stay asleep in spores. It connects the tiny world of molecules to the big world of human health.

A proteome is the entire set of proteins expressed by a genome, cell, tissue, or organism at a specific time.

While a genome provides the blueprint, the proteome represents the actual functional tools being used under defined conditions. Proteomics is the scientific study of these protein sets. Because different cells perform different tasks, they often possess unique proteomes. For example, a multicellular organism has different proteomes in different cell types. Even small structures like mitochondria have their own specific proteomes, which can consist of more than 3,000 distinct proteins.

Scientists use several complex methods to study these protein collections. One common technique is two-dimensional gel electrophoresis. This process separates proteins in two stages. First, isoelectric focusing separates them based on their electrical charge. Second, SDS-PAGE separates them by their molecular weight. The resulting gel is stained with substances like silver or Coomassie brilliant blue to make the proteins visible as distinct spots.

Another essential tool is mass spectrometry, which identifies proteins by measuring their mass.

Methods like peptide mass fingerprinting work by cleaving proteins into short peptides to match them against databases. Tandem mass spectrometry can further provide sequence information by isolating and colliding peptides with gas to produce fragment ions.

Proteomes vary significantly in size and complexity across different life forms. In viruses, the proteome is relatively well-defined and can range from about 3 to 1,000 proteins. Bacteria typically have proteomes ranging from 500 to 10,000 proteins. Eukaryotes, such as humans, are much more complicated due to a process called alternative splicing. In this process, more than one protein can be produced from a single gene. While the human genome encodes about 20,000 proteins, some estimates suggest there could be as many as 92,179 proteins when including splicing variants. This complexity makes mapping the human proteome a massive scientific challenge.

The concept of the proteome is relatively recent in scientific history. Marc Wilkins coined the term "proteome" in 1994. He introduced the idea during a symposium in Siena, Italy, titled "2D Electrophoresis: from protein maps to genomes." The term was officially published in 1995 as part of his PhD thesis. Since then, several major initiatives have attempted to map the human proteome. These include the Human Proteome Map, ProteomicsDB, and the Human Proteome Project (HPP). As of October 2020, the HPP published a high-stringency blueprint covering more than 90% of predicted protein-coding genes.

Proteomics plays a vital role in modern medical research, particularly in oncology. By analyzing the proteome, researchers can determine the presence of different cancer types.

Proteomic studies help identify how likely a cancer is to undergo metastasis, which is the spread of cancer. For example, studies on bladder cancer cell lines identified 36 unregulated and 74 down-regulated proteins. In ovarian cancer, specific biomarkers like α-enolase (ENOA) and peroxiredoxin (PRDX2) have been identified. This information allows for personalized medicine, where drug cocktails are tailored to a patient's specific proteomic profile.

Researchers also study the proteome to understand biological variability and hidden structures. Some proteins belong to the "dark proteome," a term coined by Perdigão and colleagues. This refers to protein regions that lack detectable sequence homology to known three-dimensional structures. In eukaryotes and viruses, the dark proteome can make up 44% to 54% of the total proteome. Furthermore, small changes like single amino acid polymorphisms (SAPs) can create different "proteoforms." These variations contribute to the immense diversity of proteins found within a single organism.

Finally, proteomics connects to broader biological systems and evolutionary theories. There is a concept known as "proteomic constraint." This theory suggests that an organism's DNA repair capacity is positively correlated with its genome information content. This information content is also related to the size of the proteome. In bacteria, archaea, and DNA viruses, researchers have observed that DNA repair genes are subject to selection pressure proportional to the amount of information in a genome. By studying these connections, scientists gain a deeper understanding of how life maintains its genetic integrity through protein activity.