Signalein

Signalein is a hypothetical signaling molecule used in educational models and speculative research on intercellular communication and synthetic biology. In the conceptual framework, Signalein is described as a small organic compound capable of crossing the plasma membrane and binding to a designated receptor on target cells, named the Signalein receptor (SIR). Upon binding, Signalein activates a downstream signal transduction cascade that influences transcriptional programs or metabolic responses, allowing researchers to explore how signals propagate, amplify, or attenuate within a cellular network.

In proposed systems, Signalein acts as a controllable switch: its extracellular concentration modulates receptor occupancy, producing graded or switch-like responses depending on network topology and feedback. Because it is fictional, Signalein is not an approved reagent for clinical or industrial use, and it remains a teaching and modeling tool rather than a physical chemical with validated properties.

Origin and usage: The Signalein concept emerged in theoretical discussions of signaling networks in the 2010s and has been incorporated into textbooks, online simulations, and thought experiments to illustrate core principles such as dose–response, ultrasensitivity, and robustness to perturbations.

See also: Signaling molecule, Receptor (biochemistry), Signal transduction, Synthetic biology.