Signalliganden

Signalliganden is a proposed class of signaling ligands in cellular communication theory. The term is used to describe a family of extracellular molecules that influence receptor activity through biased signaling and multivalent interactions. In this framework, signalliganden differ from conventional ligands by their ability to simultaneously engage multiple receptor units and stabilize specific receptor conformations, thereby preferentially activating certain intracellular pathways over others.

Etymology and conceptually related ideas are linked to the words signal and ligand, with the suffix -anden adopted in some Northern European scientific writings to denote a plural class. As a concept, signalliganden are discussed in relation to receptor families such as receptor tyrosine kinases and G protein–coupled receptors, where their multivalency and affinity can alter dimerization status, receptor clustering, or allosteric modulation.

Mechanisms attributed to signalliganden include high-affinity binding to extracellular domains, facilitation of receptor dimer formation, and stabilization of biased signaling states. They may be produced by specific cell types or released via vesicular trafficking and can act in autocrine or paracrine fashion. Experimental evidence is primarily indirect, relying on proteomic detection, binding assays, and pathway analysis in cell culture models.

Signalliganden are a topic of ongoing theoretical and experimental interest, with potential implications for targeted therapies and diagnostic approaches. Challenges remain in defining their precise molecular identities, distinguishing them from conventional ligands, and translating bidirectional signaling effects into clinical applications.