Juxtacrine

In biology, juxtacrine signalling (or contact-dependent signalling) is a type of cell / cell or cell / extracellular matrix signalling in multicellular organisms that requires close contact. Hence, this stands in contrast to releasing a signaling molecule by diffusion into extracellular space, or the use of long-range conduits like membrane nanotubes and cytonemes (akin to 'bridges'), or the use of extracellular vesicles like exosomes or microvesicles (akin to 'boats'). There are three types of juxtacrine signaling:

Additionally, in unicellular organisms such as bacteria, juxtacrine signaling refers to interactions by membrane contact. The term "juxtacrine" was originally introduced by Anklesaria et al. (1990) to describe a possible way of signal transduction between TGF alpha and EGFR.

Juxtacrine signaling has been observed for some growth factors, cytokine and chemokine cellular signals, playing an important role in the immune response. It has a critical role in development, particularly of cardiac and neural function. Other types of cell signaling include paracrine signalling and .

In this type of signaling, a cell places a specific ligand on the surface of its membrane, and subsequently another cell can bind it with an appropriate cell surface receptor or cell adhesion molecule. An important example is the Notch signalling, notably involved in neural development.

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