pathone

Pathone is a hypothetical molecular signaling component used in theoretical biology to illustrate how cells might couple metabolic status to gene expression. In this conceptual framework, Pathone acts as a modular gate within signaling networks, receiving inputs from metabolic sensors and translating them into transcriptional responses that affect cellular plasticity and fate decisions.

The name Pathone combines the idea of a pathway gate with the common protein suffix -one, and it has been used in several modeling studies since the early 2010s as a neutral placeholder for a central signaling node.

Proposed mechanism: Pathone is imagined as a bifunctional protein with a sensor domain that binds a metabolite indicative of energy or redox state, and a regulatory domain that recruits downstream kinases or transcriptional co-regulators. In models, Pathone's activity can be modulated by post-translational modifications and by interactions with a partner receptor, PathR, allowing it to switch between active and inactive states. Through these interactions, Pathone is proposed to influence key transcription factors and thus alter expression programs.

Evidence and status: There is no experimentally validated native Pathone protein in current biological datasets. Pathone remains a theoretical construct used to explore questions about signaling topology, robustness, and the integration of metabolic signals with gene regulation in computational studies.

Variations and related concepts: Some models posit isoforms Pathone-A and Pathone-B with different binding partners. Related ideas include signaling hubs, adaptor proteins, and gatekeeper nodes in cellular networks.