Proteida

Proteida refers to a proposed, but not universally accepted, taxonomic kingdom that would encompass all proteins. The concept originated as a way to classify these fundamental biological molecules based on their shared characteristics and importance in living organisms. Proteins are essential macromolecules composed of amino acid chains that perform a vast array of functions within cells, including catalyzing metabolic reactions, DNA replication, responding to stimuli, providing structure, and transporting molecules.

The idea of a "proteida" kingdom suggests a distinct biological realm separate from existing kingdoms like Animalia, Plantae, Fungi, Protista, and Bacteria/Archaea. Proponents argue that proteins, as the direct products of gene expression and the primary functional agents in biological processes, warrant their own classification. This would highlight their central role in life and provide a framework for studying their evolution and diversity independently of the organisms that produce them.

However, the concept of proteida faces significant challenges within the scientific community. Current biological classification systems are based on evolutionary relationships and shared ancestry, typically at the cellular or organismal level. Since proteins are produced by cellular organisms and are not independently reproducing entities, fitting them into a traditional kingdom structure is problematic. Furthermore, the sheer diversity and dynamic nature of proteins, constantly evolving and interacting, make a static kingdom classification difficult to define and maintain. For these reasons, proteida remains a speculative concept rather than an established taxonomic rank.