The proteome, which is the assortment of proteins found in a single cell in a specific environment, varies greatly from one type of cell to another, according to Annenberg Learner. For example, a typical bacterial cell contains more than 4,000 proteins, while mammals, including humans, require upwards of 100,000 different proteins to function.
Genetics Home Reference explains that proteins are made up of chains of amino acids that form sequences that determine the nature of the proteins. There are 20 different types of amino acids, and the proteins they form, though numerous, are grouped into a few major categories: antibodies, enzymes, messengers, structural components and transport or storage proteins.
The purpose of antibodies is to bind foreign particles to protect the body. Enzymes are involved in the many chemical reactions that take place in cells and help in the formation of new molecules. Messenger proteins transmit signals throughout the body to coordinate its processes. Structural proteins provide support for the cells and allow for movement. To carry small particles and molecules from one location to another, the body relies on transport and storage proteins. The complexity of proteins allows them to carry out most of the work within a cell and to regulate and assist many of the body's most complex processes