Lipid-driven Src self-association modulates its transformation capacity

Area of Science:

• Biochemistry
• Cell Biology
• Molecular Oncology

Background:

• Src tyrosine kinase is crucial for cell growth and adhesion, with deregulation linked to cancer.
• While Src associates with the plasma membrane, the influence of membrane lipids on its regulation is not well understood.

Purpose of the Study:

• To investigate the role of membrane lipids in regulating Src tyrosine kinase activity and self-association.
• To elucidate the structural basis and functional consequences of lipid-mediated Src self-association.

Main Methods:

• In vitro and in vivo assays using human cells to study Src self-association.
• Site-directed mutagenesis of the lysine cluster in the Src SH4 region.
• Formation of protein-lipid condensates using supported lipid bilayers and purified Src domains.

Main Results:

• Src self-associates via a lipid-mediated lysine cluster in its SH4 region.
• Mutating the lysine cluster affects Src self-association and its transforming potential in human cells.
• Full-length Src and its N-terminal regulatory element form micron-sized, lipid-anchored condensates, while the isolated SH4 domain forms smaller clusters.

Conclusions:

• Lipid-mediated kinase self-association is a novel regulatory mechanism for Src tyrosine kinase.
• This mechanism, involving lysine clusters and membrane lipids, may be relevant for other membrane-associated signaling proteins.