Nature of plasmalemmal functional "hemichannels"

Area of Science:

• Molecular Biology
• Cell Biology
• Biophysics

Background:

• The molecular basis of non-junctional membrane conductance, attributed to hemichannels, remains contentious.
• Proteins like innexins, connexins, and pannexins share functional similarities, complicating identification.
• Overlapping tissue distribution of connexins and pannexins in vertebrates further complicates distinguishing their roles.

Purpose of the Study:

• To provide an updated overview of functional hemichannel research.
• To discuss recent findings on the molecular identity of hemichannels.
• To focus on the roles of connexin43 and pannexin1 in hemichannel activity.

Main Methods:

• Literature review of recent studies on hemichannel proteins.
• Analysis of functional and molecular data differentiating connexin and pannexin channels.
• Discussion of proposed criteria for identifying hemichannel-mediated events.

Main Results:

• Recent research attempts to establish criteria to distinguish connexin- from pannexin-mediated hemichannel activity.
• Focus on connexin43 and pannexin1 highlights ongoing debates and recent findings.
• The complexity arises from shared properties like permeability and sensitivity to blockers.

Conclusions:

• Distinguishing between connexin and pannexin hemichannels requires careful experimental design.
• Further research is needed to definitively identify the protein constituents of functional hemichannels.
• Understanding hemichannel composition is vital for elucidating their roles in cellular processes.