Tensionin

Tensionin is a term used to describe a proposed class of mechanosensitive scaffold proteins that are thought to transduce mechanical tension at cell–substrate and cell–cell interfaces into biochemical signals. The concept of tensionin arose in theoretical discussions of how cells sense and respond to physical forces, and it is named by analogy to other protein families that end in the suffix -in.

History and status

The word tensionin refers to a hypothetical module rather than an experimentally confirmed protein sequence. As of now, tensionin remains a speculative concept cited mainly in modeling studies and reviews of mechanotransduction. No consensus has identified a native tensionin protein or confirmed its presence across species.

Structure and predicted features

Tensionin is predicted to have a modular architecture including an N-terminal force-sensing domain, a central coiled-coil stalk, and a C-terminal scaffolding domain with binding motifs for partner proteins. In proposed models, tensionin would oligomerize to bridge the actin cortex with adhesion complexes, enabling coordinated responses to mechanical load.

Localization and function

In theoretical frameworks, tensionin is expected to localize to focal adhesions and adherens junctions in vertebrate tissues, with possible conservation in other metazoans. Its function would be to sense applied tension, undergo conformational changes, and recruit signaling and structural effectors to regulate cytoskeletal remodeling and cell adhesion.

Mechanism and regulation

Under mechanical stretch, tensionin is hypothesized to unveil binding sites for adaptor proteins, triggering signaling pathways such as small GTPases and, in some models, downstream effectors involved in transcriptional responses. Regulation would be influenced by substrate stiffness, mechanical history, and post-translational modifications.

See also

Mechanotransduction; focal adhesion; cytoskeleton; talin; vinculin.