Kinin

A kinin is any of various structurally related polypeptides, such as bradykinin and kallidin. They are members of the autacoid family. Kinins are peptides that are cleaved from kininogens by the process of kallikreins. Kallikreins activate kinins when stimulated.

It is a component of the kinin-kallikrein system.

Their precursors are kininogens. Kininogens contain a 9-11 amino acid bradykinin sequence.

In botany, the plant hormones known as cytokinins were first called kinins, but the name was changed to avoid confusion.