SAP97 interacts with Kv1.5 in heterologous expression systems

Area of Science:

• Cardiology
• Molecular Biology
• Cell Biology

Background:

• PDZ domain-containing proteins, including SAP97 and ZO-1, are known to influence ion channel localization and clustering.
• Cardiac voltage-gated potassium channels are critical for heart rhythm and function.

Purpose of the Study:

• To investigate the interaction between SAP97 and the cardiac potassium channel Kv1.5.
• To determine the role of SAP97 and ZO-1 in the function and trafficking of Kv1.5 channels.

Main Methods:

• Immunocytochemistry in cardiac myocytes to assess protein colocalization.
• Transient transfection in COS-7 cells to study protein complex formation and co-immunoprecipitation.
• Functional analysis in Xenopus oocytes to measure potassium currents.

Main Results:

• SAP97 and Kv1.5 were found to colocalize in cardiac myocytes at specific membrane domains.
• SAP97 and Kv1.5 formed perinuclear clustered complexes in transfected cells, dependent on Kv1.5's C-terminal residues.
• Coexpression with SAP97 augmented Kv1.5-encoded potassium currents in oocytes, while ZO-1 did not show similar interactions or functional effects.

Conclusions:

• SAP97 interacts with Kv1.5 and modulates its function, suggesting a role in regulating cardiac potassium channel activity.
• The interaction between SAP97 and Kv1.5 is specific and impacts channel function, unlike the interaction with ZO-1.
• These findings highlight SAP97 as a potential key regulator of Kv1.5 channel function in the heart.