Deciphering the Molecular and Functional Basis of RHOGAP Family Proteins: A SYSTEMATIC APPROACH TOWARD SELECTIVE...

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• RHO GTPase-activating proteins (RHOGAPs) are key regulators of RHO protein signaling, impacting cellular processes like motility and growth.
• The specificity of most RHOGAP family members remains largely uncharacterized.
• Understanding RHOGAP function is crucial for deciphering cellular regulation.

Purpose of the Study:

• To comprehensively investigate the sequence-structure-function relationship between RHOGAPs and RHO proteins.
• To determine the substrate specificity and catalytic efficiency of RHOGAP domains.
• To identify critical determinants for binding and catalysis between RHOGAPs and RHO proteins.

Main Methods:

• Database searches to identify human RHOGAPs.
• In vitro activity assays of 14 RHOGAP representatives against 12 RHO proteins.
• In silico analysis combining sequence and structure data.
• Real-time activity determination.

Main Results:

• Identified 66 distinct human RHOGAPs, with 57 possessing a catalytic domain.
• Structurally verified hot spots at the RHOGAP-RHO protein interface critical for binding and catalysis.
• Found the RHOGAP domain to be nonselective and inefficient in cell-free conditions.
• Demonstrated the activity of 14 RHOGAPs against 12 RHO proteins.

Conclusions:

• The RHOGAP catalytic domain alone exhibits low substrate specificity and efficiency.
• Other domains within RHOGAPs are proposed to confer substrate specificity.
• Additional domains likely fine-tune RHOGAP catalytic efficiency within the cellular environment.