Biology subjects

Andriani, R. T.

Publications and source records attributed to Andriani, R. T..

3 recordsLinked to original sources

bioRxiv2026

PI(4,5)P2-dependence of GABAA receptor channel function revealed by optogenetic manipulation of a binding site

ABSTRACT/SUMMARYIonotropic GABAA receptors (GABAARs) mediate fast inhibitory neurotransmission in mammalian brains. While recent structural studies have identified that phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], a well-established regulator of numerous ion channels, binds to the 1 subunits of GABAARs, the functional relevance of this binding has remained elusive. Here, we combine electrophysiology, molecular dynamics simulations, and a recently developed caged lysine technology to define the role of PI(4,5)P2 in GABAARs. We show that GABAARs are insensitive to acute PI(4,5)P2 depletions by voltage-sensing phosphatase, but sensitivity is conferred by neutralizing the K311 binding site, indicating high-affinity binding. Caging of K311 by use of genetic code expansion recapitulated phenotypes of K311 mutant, conferring sensitivity to PI(4,5)P2 depletion, whereas uncaging restored insensitivity. Furthermore, caging K311 revealed decelerated activation, which then can be accelerated by uncaging. Additionally, PI(4,5)P2-dependence extends to glycine receptors, suggesting PI(4,5)P2 is an important endogenous phospholipid modulator of inhibitory receptor channels.

biophysics↗

bioRxiv2024

Zinc is a Key Regulator of the Sperm-Specific K+ Channel (Slo3) Function

The voltage- and pH-gated Slo3 potassium channel is exclusively expressed in mammalian spermatozoa. Its sensitivity to both voltage and alkalization plays a crucial role in sperm fertility, which is tightly coupled to the capacitation process. Here we show that sperm-enriched divalent cation Zn2+ undergoes dynamic alteration in spermatozoa during capacitation. We also found that intracellular Zn2+ regulates alkalinization-induced hyperpolarization in mouse spermatozoa which is mediated by Slo3 channel. Further examination of zinc regulation in mouse Slo3 (mSlo3) revealed that, in Xenopus oocyte expression system, intracellular zinc directly inhibits mouse Slo3 currents in dose-dependent manner at micromolar concentrations, with exceptionally slow dissociation. By combining MD simulations and electrophysiology, we also identified amino acid residues contributing to the Zn2+ slow dissociation from Slo3 channels. Our studies uncover the importance of intracellular zinc dynamics and its regulatory role in ion channels during sperm capacitation.

physiology↗

bioRxiv2020

Voltage-clamp fluorometry analysis of structural rearrangements of ATP-gated channel P2X2 upon hyperpolarization

The gating of the ATP-activated channel P2X2 has been shown to be dependent not only on [ATP] but also on membrane voltage, despite the absence of a canonical voltage-sensor domain. We aimed to investigate the structural rearrangements of the rat P2X2 during ATP- and voltage-dependent gating by voltage-clamp fluorometry technique. We observed fast and linearly voltage-dependent fluorescence intensity (F) changes at Ala337 and Ile341 in the TM2 domain, which could be due to the electrochromic effect, reflecting the presence of a converged electric field here. We also observed slow and voltage-dependent F changes at Ala337, which reflect the structural rearrangements. Furthermore, we identified that the interaction between Ala337 in TM2 and Phe44 in TM1, located in close proximity in the ATP-bound open state, is critical for activation. Taken together, we propose that the voltage dependence of the interaction in the converged electric field underlies the voltage-dependent gating.

biophysics↗