Modulating cells' chloride channels

December 16, 2020

Laboratory cell experiments and computer simulations have revealed molecular mechanisms regulating a protein channel responsible for transporting chloride and other charged molecules across cell membranes. The findings were published in the Proceedings of the National Academy of Sciences (PNAS).

"Our findings could help provide clues for developing treatments for diseases associated with this channel's malfunction, including some cancers, cystic fibrosis, and neurological pain," says molecular neurophysiologist Byung-Chang Suh of Daegu Gyeongbuk Institute of Science and Technology (DGIST), who led the study.

Transmembrane 16A (TMEM16A) is a chloride channel found in cell membranes. It is involved in diverse physiological roles, including small muscle contraction, regulating nerve excitability and cell volume, and detecting 'bad' heat by sensory nerve fibres. Scientists already know quite a lot about this protein. Now, Suh and his colleagues in Korea and the US have revealed some of the molecular underpinnings of its interaction with a cellular signalling phospholipid called PIP2.

PIP2 is found in the inner leaflet of the cell's membrane. PIP2 binding to TMEM16A regulates the amount of chloride, and thus the electric current, that passes through it.

The team found that PIP2 acts differently on two variations of the TMEM16A channel. Human cell experiments showed that PIP2 depletion reduced the current passing through the version called TMEM16A(ac) but not through TMEM16A(a). They also found that the energy-carrying molecule called ATP was needed for current to run through both types of the channel.

Structural analyses and computer simulations showed that phosphorylation - or adding a phosphate group¬ - of a specific amino acid on TMEM16A changed how PIP2 bound to that part of the chloride channel, with different effects on TMEM16A(ac) and TMEM16A(a).

"Our investigations provide an important foundation for mechanistic understanding of TMEM16A activity, suggesting its function depends on the channel variant, and is regulated by PIP2 binding and channel phosphorylation," says Suh. The scientists hope their investigations will assist other studies of similar cell membrane proteins, in addition to supporting drug development research.

They recommend further studies to understand how the structures of TMEM16A variants impact its physiological functions in various tissues.

DGIST (Daegu Gyeongbuk Institute of Science and Technology)

Related Protein Articles from Brightsurf:

The protein dress of a neuron
New method marks proteins and reveals the receptors in which neurons are dressed

Memory protein
When UC Santa Barbara materials scientist Omar Saleh and graduate student Ian Morgan sought to understand the mechanical behaviors of disordered proteins in the lab, they expected that after being stretched, one particular model protein would snap back instantaneously, like a rubber band.

Diets high in protein, particularly plant protein, linked to lower risk of death
Diets high in protein, particularly plant protein, are associated with a lower risk of death from any cause, finds an analysis of the latest evidence published by The BMJ today.

A new understanding of protein movement
A team of UD engineers has uncovered the role of surface diffusion in protein transport, which could aid biopharmaceutical processing.

A new biotinylation enzyme for analyzing protein-protein interactions
Proteins play roles by interacting with various other proteins. Therefore, interaction analysis is an indispensable technique for studying the function of proteins.

Substituting the next-best protein
Children born with Duchenne muscular dystrophy have a mutation in the X-chromosome gene that would normally code for dystrophin, a protein that provides structural integrity to skeletal muscles.

A direct protein-to-protein binding couples cell survival to cell proliferation
The regulators of apoptosis watch over cell replication and the decision to enter the cell cycle.

A protein that controls inflammation
A study by the research team of Prof. Geert van Loo (VIB-UGent Center for Inflammation Research) has unraveled a critical molecular mechanism behind autoimmune and inflammatory diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis.

Resurrecting ancient protein partners reveals origin of protein regulation
After reconstructing the ancient forms of two cellular proteins, scientists discovered the earliest known instance of a complex form of protein regulation.

Sensing protein wellbeing
The folding state of the proteins in live cells often reflect the cell's general health.

Read More: Protein News and Protein Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to