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1.D.280. The Vesicle Fusion-based Bionic K+ Porin (VFBP) Family  

The transport of K+ across the cell membrane is of vital importance in many important biological activities, including cardiac contraction, muscle contraction, hormone secretion, and changes in neuronal excitability. For cardiac contraction, K+ channels play an important role in the formation of resting potential, automatic generation of excitation, excitation conduction, and final contraction of cardiomyocytes. Specifically, K+ channels are membrane proteins in the cell membrane that catalyze K+ ions transport across the cardiomyocyte membrane to form the potential difference of outward potassium current and maintain the resting membrane potential.  In concert with other ion channels, K+ channels can balance the electrophysiological process of the entire excitation–contraction coupling of cardiomyocytes and regulate electrical excitability in the heart. The dysfunction of the K+ channel can lead to the disturbance of potassium current in heart cells, which can lead to cardiac electrophysiological disorders, and eventually produce related cardiovascular diseases such as long QT syndrome, heart failure, and arrhythmia. Therefore, the regulation of K+ channel activity and function has important significance in heart health and disease (Shen et al. 2024). 

The VFBPs are composed of bionic porin wrapped in large unilamellar vesicles (LUVs), which are similar to the barrel structure of porin, with an inner diameter of 1.5 nm. The VFBP can spontaneously insert into the cell membrane during membrane fusion to form transmembrane ion channels, leading to the transport of K+ ions on the cell membrane. Molecular dynamics (MD) studies have shown that the negative charge provided by the carboxyl group modified on the VFBP port reduces the energy barrier of K+ ions across channels and can promote K+ ion transport at a rate of 108 per second, which is comparable to the natural ion channels (Shen et al. 2024). 

Bionic porins are created by sonication-assisted cutting of long carbon nanotubes synthesized by chemical vapor deposition (CVD).  Transmission electron microscopy (TEM) images of bionic porin indicate that the mean inner diameter of bionic porins is 1.5 nm, and the length locates in the range of 5–15 nm. The inner diameter of 1.5 nm can ensure the passage of hydrated K+ ions, and the length of about 10 nm enables its capability to be inserted on the lipid bilayer across the membrane (Shen et al. 2024).

References associated with 1.D.280 family:

Shen, X., Q. Lu, T. Peng, Y. Zhang, W. Tan, Y. Yang, J. Tan, and Q. Yuan. (2024). Bionic Potassium Ion Channel in Live Cells Repairs Cardiomyocyte Function. J. Am. Chem. Soc. 146: 19896-19908. 38982560