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Deduction of Homology Between Cell Membrane and Nuclear Pore Tetramers Based on Evolution Theory and Existing Data

发布时间：

2026-07-29

Deduction of Homology Between Cell Membrane and Nuclear Pore Tetramers Based on Evolution Theory and Existing Data

Sun Zuodong

The potassium ion channels on the cell membrane and nuclear pore channels on the nuclear envelope of eukaryotic cells have long been regarded by academia as two unrelated membrane protein systems. Functional potassium channels on the cell membrane assemble into an inverted conical pore via four subunits, while nuclear envelope channels also adopt a tetrameric windmill spatial conformation. Drawing on established achievements in modern evolutionary biology and structural biology, alongside the logic of evolution theory, a complete chain of homologous evolutionary deduction can be constructed to provide theoretical support for the Origami Windmill Homology Model.

Evolutionary theory distinguishes two types of structural similarity: convergent evolution and homologous evolution. Convergent evolution refers to proteins of distinct evolutionary origins developing similar morphologies under environmental selective pressure. Homologous evolution describes proteins descending from a single ancestral precursor protein that diverge in function following gene duplication, evolving into molecular machineries with comparable morphology yet differentiated roles. Multiple lines of evidence collectively indicate that tetrameric channels on cell membranes and nuclear envelopes are most likely products of homologous evolution.

First, both share a conserved origami windmill spatial architecture. The classic potassium channel structure resolved by MacKinnon demonstrates that functional potassium channels consist of four surrounding subunits resembling folded windmill blades, forming an inverted tapered central pore. Cryo-electron microscopy reconstructions of the core nuclear pore channel in recent years likewise reveal a four-fold rotationally symmetric Origami Windmill Model conformation. Beyond superficial resemblance, the physical logic governing their spatial folding is strikingly identical. This Origami Windmill Model is not a random structural outcome; four-fold symmetry constitutes a universal assembly blueprint for membrane pore proteins in archaea and early eukaryotes. The probability that two independent protein lineages would converge to replicate this highly specialized geometric configuration is extremely low—convergent evolution would require incurring the physical energetic cost of independent folding events multiple times. Homologous evolution, by contrast, readily accounts for this shared structural trait.

Second, this model aligns with the evolutionary timeline of eukaryotic origins. The prevailing academic consensus holds that all eukaryotes share a last eukaryotic common ancestor (LECA). Ion channels first emerged on the cell membranes of ancestral archaea to maintain transmembrane ion gradients and generate bioelectricity. As primitive cells gradually evolved endomembrane systems and nascent nuclei, tandem duplication of the ancestral membrane channel gene occurred. One gene copy remained localized to the cell membrane to regulate global cellular electrical signaling, while a second copy relocated to the newly formed nuclear envelope and underwent modification to form nuclear envelope channels, mediating ion exchange between the nucleoplasm and cytoplasm. This trajectory fully conforms to the canonical evolutionary paradigm of "gene duplication followed by functional differentiation".

Third, coordinated physiological functions corroborate the evolutionary logic. Potassium and sodium flux across the cell membrane establishes the cell resting potential, and nuclear pore channels rely on cytoplasmic ion supply to sustain the intranuclear microenvironment. It would be difficult for two independently evolved channel systems to develop such tightly coupled electrical coordination. Only a shared ancestral molecular origin can explain their innate signal compatibility, which in turn generates the delayed electrical coupling effect between cell and nuclear membranes and establishes a regulatory pathway linking bioelectricity and epigenetic inheritance.

An important caveat must be clarified: homology does not require full conservation of amino acid sequences. After over a billion years of evolution, the primary amino acid sequences of these proteins may have diverged completely, yet the underlying physical principles governing their folding into windmill-shaped structures—the logic of tetrameric assembly and core spatial scaffold—have been rigidly preserved by natural selection. This also explains the widespread phenomenon of homologous proteins exhibiting highly similar three-dimensional structures despite drastically divergent primary sequences.

This homologous deduction remains a theoretical hypothesis rather than a definitive conclusion, yet it opens a novel research frontier. Subsequent experimental validation approaches may include structural alignment, homology modeling, and phylogenetic tracing of archaeal proteins. If this homology hypothesis is experimentally verified, it will dismantle the longstanding research paradigm that segregates cell membrane channels and nuclear pore complexes, reshaping our fundamental understanding of the origins of cellular bioelectricity and the underlying logic of genetic signal regulation.