User:Carlyneville/sandbox

A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions (Zn2+) which stabilizes the fold. It was originally coined to describe the finger-like appearance of a hypothesized structure from the African clawed frog (Xenopus laevis) transcription factor IIIA. However, it has been found to encompass a wide variety of differing protein structures in eukaryotic cells. Xenopus laevis TFIIIA was originally demonstrated to contain zinc and require the metal for function in 1983, the first such reported zinc requirement for a gene regulatory protein followed soon thereafter by the Krüppel factor in Drosophila. It often appears as a metal-binding domain in multi-domain protein.

Proteins that have zinc fingers (zinc finger proteins) are classified into several different structural families. Unlike many other clearly defined supersecondary structures such as Greek keys or β hairpins, there are a '"many different'" types of zinc fingers, each with a unique three-dimensional architecture. "'A certain zinc finger protein's class can be classified'" by this three-dimensional structure, but it can also be recognized based on the primary structure of the protein or the identity of the ligands coordinating the zinc ion. '"Despite'" the large variety of these proteins, however, the vast majority typically function as interaction modules that bind DNA, RNA, proteins, or other small, useful molecules, and variations in structure serve primarily to change the binding specificity of a particular protein.