NOTportteina

NOTportteina is a fictional regulatory protein used in speculative biology and science education to demonstrate how a NOT logic gate could be implemented in a cellular context. The name combines the logical negation operator NOT with portteina, a coined suffix used to designate a hypothetical protein family.

In the standard fictional model, NOTportteina is a small cytosolic protein of approximately 20 to 25 kilodaltons. It is described as having an intrinsically disordered N-terminal region that mediates regulatory interactions and a conserved C-terminal domain that binds to a transcriptional regulator. When a designated inducer is present, NOTportteina sequesters its partner and reduces transcription of a reporter gene, producing an output that is the logical negation of the input.

Within the imagined organism, NOTportteina participates in a simple gene circuit alongside a promoter and an activator, forming a NOT gate whose output is inverted with respect to the input signal. The concept is primarily used as a teaching tool to discuss how protein-protein interactions can realize logical functions in biology, rather than as a claim about an experimentally verified protein.

Scholarly reaction has been to treat NOTportteina as a hypothetical example, emphasizing that it belongs to speculative literature and highlighting the importance of distinguishing fictional models from empirical data. It is sometimes cited in discussions of synthetic biology pedagogy and the design of gene circuits.