An intact connexin N-terminus is required for function but not gap junction formation

Area of Science:

• Cell Biology
• Molecular Biology
• Biophysics

Background:

• Connexin N-termini influence protein trafficking, oligomerization, and channel gating.
• Connexin37 (CX37) is a key component of gap junctions, facilitating intercellular communication.

Purpose of the Study:

• To investigate the role of the CX37 N-terminus in gap junction formation and function.
• To determine the effects of N-terminal deletions and mutations on CX37 channel activity.

Main Methods:

• Site-directed mutagenesis to create CX37 N-terminal deletion and alanine-substitution mutants.
• Transient transfection of HeLa cells to assess gap junction plaque formation.
• Microinjection and Xenopus oocyte expression systems to evaluate channel function and conductance.

Main Results:

• Mutants with at least nine N-terminal amino acids formed gap junction plaques.
• No N-terminal mutant constructs exhibited hemichannel or gap junction channel function.
• N-terminal mutants inhibited wild-type CX37 hemichannel conductance, indicating co-oligomerization.

Conclusions:

• The CX37 N-terminus is essential for hemichannel gating and intercellular communication.
• Significant portions of the N-terminus can be deleted without abolishing gap junction plaque formation.
• N-terminal domain interactions are critical for regulating connexin channel activity.